Question

the age of father is thrice times of his son ,10 years after ,the fathers age is twice of that of his son.the father age will be 60 after ____ years

Answer 1

After 30 yrs the father will turn 60 since his age in present is 30. and the son's age is 10 yrs.

Answer 2

let the father's age be x and age of his son be y years.
By first condition,
x=3y
x-3y=0. ....(1)
By second condition,
x+10=2(y+10)
x+10=2y+20
x-2y=10. .....(2)
Subtracting eqn(1) from eqn(2),
x-2y-(x-3y)=10-0
x-2y-x+3y=10
y=10

Put y=10 in eqn(1),
x-3×10=0
x-30=0
x=30 yrs.

So father's age will be 60 after 60-x years=60-30 years=30 years.

Hence after 30 years fathers age will be 60.