Mr Manu is 4 times as old as his son, Adu. 7 years ago the sum of their ages was 76. How old is Adu?
- 22years
- 12years
-
18years
- 15 years
The correct answer is: C
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.