Use the following information below to answer the question Ojo bought a bicycle for ₦20,000, and repaired it at a cost of ₦5,000. He then sold the bicycle f...

Here, "expenses" refers to the repair cost, since this is the additional expense incurred beyond the original purchase, and "cost" refers to the original cost price of the bicycle before repairs. The percentage of expenses over cost measures how large the repair expense is relative to what the bicycle was originally bought for.

1. Expenses (repair cost): \( \text{₦}5{,}000 \)
2. Cost price of bicycle: \( \text{₦}20{,}000 \)
3. Percentage: \( \dfrac{5{,}000}{20{,}000} \times 100\% = 25\% \)

So the expenses represent 25% of the cost price. This calculation uses the original cost price of \( \text{₦}20{,}000 \) as the base, not the selling price or the combined cost, because the question specifically asks for expenses as a percentage of cost.

A common mistake is dividing the repair cost by the total cost of \( \text{₦}25{,}000 \) instead of the original cost price of \( \text{₦}20{,}000 \); always check which figure the question names as the base before dividing.

When calculating a percentage of one value over another, always confirm which figure the question defines as the denominator.