WAEC Mathematics 2023 Paper

Concept:This problem uses linear equations based on age relationships.Explanation:Let Adu’s current age be $y$ years.Then Mr Manu’s current age is $4y$ years, because he is 4 times as old as Adu.7 years ago, Mr Manu’s age was $4y - 7$.7 years ago, Adu’s age was $y - 7$.The sum of their ages 7 years ago was 76.So, $(4y - 7) + (y - 7) = 76$.Simplify: $5y - 14 = 76$.Add 14 to both sides: $5y = 90$.Divide by 5: $y = \frac{90}{5} = 18$.Therefore, Adu is 18 years old.Answer:C. 18 years