Question

A father's age is 4 times as that of his son's age. in 5 years time, the father will be 3 times as old as his son. what are their present ages?​

Answer 1

present age of son = 10

present age of father = 40

Explanation:

Let, present age of son be 'x'

present age of father be 'y'

y = 4x→ equation ( i )

After five years,

Son's age = x + 5

father's age = y + 5

According to Question,

`y + 5 = 3(x + 5)`

Put the value of y from equation ( i )

`4x + 5 = 3(x + 5)`

Distribute 3 through the parentheses

`4x + 5 = 3x + 15`

Move variable to L.H.S and change it's sign

Similarly, Move constant to R.H.S. and change its sign

`4x - 3x = 15 - 5`

Collect like terms

`x = 15 - 5`

Calculate the difference

`x = 10`

Now, put the value of X in equation ( i ) in order to find the present age of father

`y = 4x`

plug the value of X

`= 4 * 10`

Calculate the product

`= 40`

Therefore,

Present age of son = 10

present age of father = 40

Hope this helps..

Best regards!!