Question

a man is thrice as old as his son. 5 years ago the man was four times as old as his son .find there present age

Answer 1

Let the age of son be x

Let his father's age be 3x

Five years ago, age of son = x - 5

Five years ago, age of father = 3x - 5

5 years ago the man was four times as old as his son = 4(x - 5)

According to the question,

3x - 5 = 4(x - 5)

3x - 5 = 4x - 20

3x - 4x = -20 + 5

$\cancel{-}$x = $\cancel{-}$15

x = 15

Present age of son is x

=> 15 years

Present age of father =. 3x

=> 3 * 15

=> 45 years

∴ The age of son and his father is 15 years and 45 years respectively.

Answer 2

Let son's age = X

Man's age = 3x

5 years ago -

son's age is x - 5

Man's age is 3x - 5

According to the given question -

3x - 5 = 4(x - 5)

3x - 5 = 4x - 20

3x - 4x = -20 + 5

- X = - 15

x = 15

Finding present ages -

son's age X = 15 years

Man's age 3x = 3(15) = 45 years.