WAEC Mathematics 2021 Paper

Concept:Import duty of 38 kobo per naira means the trader pays $0.38$ naira for every $1$ naira of the engine's cost.Explanation:Let the cost of the engine be $C$ naira.Since $100$ kobo make $1$ naira, the rate of $38$ kobo per naira is $\frac{38}{100} = 0.38$ naira per naira.Total import duty paid $= 0.38 \times C$.Given that the total duty paid is #22,800.00, we write $0.38C = 22{,}800.00$.Solve for $C$: $C = \frac{22{,}800.00}{0.38}$.Simplify: $C = \frac{22{,}800.00 \times 100}{38} = 60{,}000.00$.Answer:The cost of the engine is #60,000.00.