Inferring parental age gap – A man was 32 when his first son was born. When that son was 7, his wife was 35. What is the age difference between father and mother?

Introduction / Context:
Age differences between adults remain constant over time. The problem gives two snapshots (at son’s birth and when son reaches 7) that let us compute the constant father–mother gap quickly.

Given Data / Assumptions:

• Father's age at son's birth = 32.
• When son is 7, mother is 35; thus 7 years have passed since the birth.

Concept / Approach:
At the time the son was 7, father's age = 32 + 7 = 39. Compare with mother's 35 to get the difference. That gap equals the father–mother age difference always.

Step-by-Step Solution:
Father at son age 7: 32 + 7 = 39.Mother at that time: 35.Difference = 39 − 35 = 4 years.

Verification / Alternative check:
Any later or earlier time will retain the 4-year gap; adding/subtracting the same number to both keeps their difference constant.

Why Other Options Are Wrong:
They contradict the snapshot calculations and the invariance of the age gap.

Common Pitfalls:
Trying to average or otherwise combine the numbers instead of using the constant-difference property.

Final Answer:
4 years