Question

please answer the questions very fast because it is used for my exam. please answer both answers.

Answer 1

$let \: cost \: price \: = x \\ selling \: price = \frac{4}{5} \times x \\ loss = cp - sp \\ loss = x- \frac{4}{5} \times x \\ loss = \frac{5x - 4x}{5} = \frac{x}{5} \\ loss\% = \frac{loss}{cp} \times 100 \\ loss\% = \frac{ \frac{x}{5} }{x} \times 100 \\ loss\% = \frac{x}{5x} \times 100 = 20\%$