Question

A father is 3 times as old as his son. After 15 years, he will be twice as old as his son, what are there present ages?

Answer 1

let son age = x
father age = 3x

afer 15 year
new age of son= x + 15
new age of father = 3x + 15

A.T.Q father will be twice

3x + 15 = 2(x + 15)
3x + 15 = 2x + 30
3x - 2x = 30-15
x = 15

Son's age = 15
father' age = 3x
= 3 × 15
=45

Answer 2

Let, the present age of father be x and the present age of son be y
According to the question,
x=3y......(¡)
(x+5)=2(y+5)......(¡¡)
(¡¡),(x+15)=2(y+15)
x+15=2y+30
x-2y=30-15
x-2y=15......(¡¡¡)
Now putting x=3y in eqn (¡¡¡) we get 3y-2y =15
Y=15
Now putting Y=15in eqn 1 we get
X=45

therefore, fathers present age is 45 and sons present age is 15