Question

A father ,i know , is 4 times his son's age .and in 30 year son's age will be half of his father's age .how old are the father and son now?

Answer 1

let sons age=x
therefore fathers age=4x
according to the question after 30 years 
sons age=x+30
fathers age=4x+30
ATQ 4x+30/2=x+30
4x+30=2(x+30)
4x+30=2x+60
4x - 2x = 60-30
2x=30 
x=15 
therefore sons age=15 years
                fatehrs age=4*15=60 years

Answer 2

Given:

A father is 4 times his son's age and in 30 years, the son's age will be half of his father's age.

To find:

The present age of father and son.

Solution:

Let the present age of the son be x years.

So, according to the question, we have,

the present age of father = 4 times son's age = 4x years

After 30 years, the son's age = x + 30 years

after 30 years, the father's age = 4x + 30years

So, according to the question,

$x + 30 = \frac{1}{2} (4x + 30)$

$2x + 60 = 4x + 30$

$2x = 30$

$x = 15 years$

On putting the value of x in the present age of father i.e. 4x, we have,

$4x = 15 × 4 years$

$4x = 60 years$

Hence, the present age of father and son is 60 years and 15 years respectively.