Question

The age of father 3 years ago was 2.5 times of his sons age and after 7 years it will be twice to that of his son, the present age of the father and son will be _____.

• A. 53,20
• B. 49,21
• C. 48,20
• D. 52,23

Answer 1

The correct option is B 49,21

Let the present age of son be x and age of father be y

According to question

3 years ago

$(y-3)=2.5(x-3)\to y-3=2.5x-7.5\to y=2.5x-3.5-\left(1\right)$

After 7 years

$(y+7)=2(x+7)\to y+7=2x+14\to y=2x+7-\left(2\right)$

Solving eqs.(1) and (2)

we get $x=21,y=49$