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Interchange with Unknown - Absolute-Beginner Level: core concept mastery Interchange with Unknown ABSOLUTE BEGINNER

This skill primer 🌟 worksheet focuses on Interchange with Unknown - a key topic in Number Ranking. You'll solve 20 absolute-beginner-level problems (Worksheet 1 of 10). The primary focus is on core concept mastery. Master interchange with unknown problems, interchange with unknown reasoning questions, and interchange with unknown practice through systematic practice.

📝 Worksheet 1 of 10 • 20 questions • ⏱️ Estimated time: 20 minutes • 🎯 Absolute Beginner level

What you'll learn in this worksheet:
Your progress through Interchange with Unknown
Worksheet 1 of 10 (0% complete)

Question 1

In a row of 43 people, after interchanging positions with B, A becomes 16th from the left and 28th from the right. If B was originally 18th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 18, we can find A's original left rank = total - r2_right + 1 = 43 - 18 + 1 = 9.

Question 2

In a row of 42 people, A is 9th from the left. After interchanging positions with B, A becomes 16th from the left. B originally was 15th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 16. So A's new right rank = total - new_left + 1 = 42 - 16 + 1 = 27.

Question 3

In a row of 42 people, after interchanging positions with B, A becomes 19th from the left and 24th from the right. If B was originally 17th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 17, we can find A's original left rank = total - r2_right + 1 = 42 - 17 + 1 = 12.

Question 4

In a row of 40 people, after interchanging positions with B, A becomes 18th from the left and 23th from the right. If B was originally 14th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 14, we can find A's original left rank = total - r2_right + 1 = 40 - 14 + 1 = 11.

Question 5

In a row of 47 people, A is 12th from the left. After interchanging positions with B, A becomes 15th from the left. B originally was 17th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 15. So A's new right rank = total - new_left + 1 = 47 - 15 + 1 = 33.

Question 6

In a row of 36 people, after interchanging positions with B, A becomes 16th from the left and 21th from the right. If B was originally 14th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 14, we can find A's original left rank = total - r2_right + 1 = 36 - 14 + 1 = 12.

Question 7

In a row of 45 people, A is 9th from the left. After interchanging positions with B, A becomes 12th from the left. B originally was 14th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 12. So A's new right rank = total - new_left + 1 = 45 - 12 + 1 = 34.

Question 8

In a row of 55 people, A is 9th from the left. After interchanging positions with B, A becomes 15th from the left. B originally was 18th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 15. So A's new right rank = total - new_left + 1 = 55 - 15 + 1 = 41.

Question 9

In a row of 53 people, after interchanging positions with B, A becomes 19th from the left and 35th from the right. If B was originally 14th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 14, we can find A's original left rank = total - r2_right + 1 = 53 - 14 + 1 = 12.

Question 10

In a row of 41 people, after interchanging positions with B, A becomes 19th from the left and 23th from the right. If B was originally 10th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 10, we can find A's original left rank = total - r2_right + 1 = 41 - 10 + 1 = 15.

Question 11

In a row of 49 people, A is 11th from the left. After interchanging positions with B, A becomes 14th from the left. B originally was 18th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 14. So A's new right rank = total - new_left + 1 = 49 - 14 + 1 = 36.

Question 12

In a row of 47 people, A is 11th from the left. After interchanging positions with B, A becomes 14th from the left. B originally was 18th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 14. So A's new right rank = total - new_left + 1 = 47 - 14 + 1 = 34.

Question 13

In a row of 48 people, A is 8th from the left. After interchanging positions with B, A becomes 15th from the left. B originally was 13th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 15. So A's new right rank = total - new_left + 1 = 48 - 15 + 1 = 34.

Question 14

In a row of 45 people, A is 13th from the left. After interchanging positions with B, A becomes 21th from the left. B originally was 11th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 21. So A's new right rank = total - new_left + 1 = 45 - 21 + 1 = 25.

Question 15

In a row of 47 people, after interchanging positions with B, A becomes 17th from the left and 31th from the right. If B was originally 12th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 12, we can find A's original left rank = total - r2_right + 1 = 47 - 12 + 1 = 13.

Question 16

In a row of 49 people, A is 14th from the left. After interchanging positions with B, A becomes 22th from the left. B originally was 12th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 22. So A's new right rank = total - new_left + 1 = 49 - 22 + 1 = 28.

Question 17

In a row of 47 people, after interchanging positions with B, A becomes 12th from the left and 36th from the right. If B was originally 13th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 13, we can find A's original left rank = total - r2_right + 1 = 47 - 13 + 1 = 9.

Question 18

In a row of 45 people, after interchanging positions with B, A becomes 22th from the left and 24th from the right. If B was originally 17th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 17, we can find A's original left rank = total - r2_right + 1 = 45 - 17 + 1 = 15.

Question 19

In a row of 55 people, A is 11th from the left. After interchanging positions with B, A becomes 16th from the left. B originally was 12th from the right. What is A's new rank from the right?
After interchange, A's new left rank is 16. So A's new right rank = total - new_left + 1 = 55 - 16 + 1 = 40.

Question 20

In a row of 48 people, after interchanging positions with B, A becomes 15th from the left and 34th from the right. If B was originally 18th from the right, what was A's original rank from the left?
Since B took A's original position, and B's original right rank was 18, we can find A's original left rank = total - r2_right + 1 = 48 - 18 + 1 = 10.
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