WAEC 2023 · Paper 1 · Q7

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?

Worked solution (try it first)

Let Adu be $a$ years old now, so Mr Manu is $4a$ .
Seven years ago each was 7 years younger: $(4a - 7) + (a - 7) = 76$ , so $5a - 14 = 76$ .
Add 14 to both sides: $5a = 90$ .
Divide by 5: $a = 18$ .
Adu is 18 years old, option C.