Question

The 2 age of a couple and their son was 40 years, the son got married and a child was born just two years after their marriage. When child turned to 10 years, then the 2 age of the family becomes 38 years. What was the age of the daughter in law at the time of marriage ?
A) 12 years
B) 10 years
C) 14 years
D) 13 years

Answer 1

Let present age of P and Q be 3x and 4xrespectively.

Ten years ago, P was half of Q's age
⇒(3x−10)=12(4x−10)⇒6x−20=4x−10⇒2x=10⇒x=5

Total of their present ages
=3x+4x=7x=7×5=35

Answer 2

Q:

The 2 age of a couple and their son was 40 years, the son got married and a child was born just two years after their marriage. When child turned to 10 years, then the average age of the family becomes 38 years. What was the age of the daughter in law at the time of marriage ?

A) 12 years
B) 10 years
C) 14 years
D) 13 years

Answer:   A) 12 years 

Read Description:

Given the average age of couple and their son = 40

=> Sum of age (H +W +S) = 40×3

Let the age of daughter in law at the time of marriage = D years

Now after 10 years,

(H + S +W) + 3×12 + D +12 + 10 = 38×5
178 + D = 190

D = 190 -178 = 12 years

Hence, the age of the daughter in law at the time of marriage was 12 years.