Question 1
When Elena was born, Seema was 5 years old. The sum of their present ages is 39. Find Elena's age when Elena was half of Seema's age (this will happen 12 years ago).
Let Elena's current age = 17, Seema's current age = 22
Given: When Elena was born (0 years old), Seema was 5 years old.
Therefore, Seema is always 5 years older than Elena.
So 22 = 17 + 5 ✓
Condition: Find t such that Elena's age = ½ of Seema's age
Equation: 17 + t = ½(22 + t)
Multiply both sides by 2: 217 + 2t = 22 + t
Simplify: 217 + 2t - t = 22
217 + t = 22
t = 22 - 217
t = 22 - 34 = -12
At that time, Elena's age = 17 + -12 = 5
Verification: When Elena is 5, Seema is 10 = 10
Check: Is 5 = ½ × 10? ½ × 10 = 5.0 ✓
Note: Mathematically, this always equals the age difference (5) because:
event_age = current_a + t = current_a + (current_b - 2·current_a) = current_b - current_a = age_diff
Given: When Elena was born (0 years old), Seema was 5 years old.
Therefore, Seema is always 5 years older than Elena.
So 22 = 17 + 5 ✓
Condition: Find t such that Elena's age = ½ of Seema's age
Equation: 17 + t = ½(22 + t)
Multiply both sides by 2: 217 + 2t = 22 + t
Simplify: 217 + 2t - t = 22
217 + t = 22
t = 22 - 217
t = 22 - 34 = -12
At that time, Elena's age = 17 + -12 = 5
Verification: When Elena is 5, Seema is 10 = 10
Check: Is 5 = ½ × 10? ½ × 10 = 5.0 ✓
Note: Mathematically, this always equals the age difference (5) because:
event_age = current_a + t = current_a + (current_b - 2·current_a) = current_b - current_a = age_diff