Mr Manu is 4 times as old as his son, Adu. 7 years ago the…

Explanation

Let Mr Manu be x years old and Adu be y years old.

But Mr Manu is four times as old as Adu then, x = 4y.

7 years ago, the sum of their ages was 76.

( x - 7) + ( y - 7) = 76

x + y - 14 = 76 

x + y = 76 + 14 = 90

But x = 4y 

Therefore, 4y + y = 90

5y = 90 

y = \(\frac{90}{5}\)

y = 18

Therefore Adu is 18 years old.