Question

The cost price of 60 articles is equal to the selling price of 50 articles. The gain percentage is?

Answer 1

$cp \times 60 = sp \times 50 \\ \frac{cp}{sp} = \frac{5}{6} \\ p = sp - cp \\ p = 6 - 5 = 1 \\ p\% = \frac{p \times 100}{cp} = \frac{1 \times 100}{5} \\ p\% = 20\%$