Question

The present age of fat is four times the age of his son. After 10 years, age of father will become three times the age of his son. Find their present age

Answer 1

Let age of his son be x yrs
then,age of his father=4x
After 10 yrs
son age=10+x
father age=10+4x
ATQ
3 (10+x)=10+4x
30+3x=10+4x
3x-4x=10-30
-x=-20
x=20
So,present age of son=20yrs
And present age of father=4×20=80yrs

Answer 2

let the present age of fat be x
and his son age be y
ATP
x = 4y ------------ (1)
after 10 yrs. the age of fat is x+10
and the age of his son is y+10.
therefore, x+10 = 3 (y+10)
4y + 10 =3y +30 (since x=4y )
4y -3y = 30 -10
y = 20
the age of his son is 20 yrs.
and the age of father is 4y
= 4×20 =80