Question

7. the selling price of 10 copies is equal to the cost price of 15 copies. Find the gain percent​

Answer 1

let SP of 10 copies be x

SP of 1 copy = x/10

A/Q,

CP of 15 copies = x

CP of 1 copy = x/15

$gain\% = \frac{(SP - CP) \times 100}{ CP} \\ \\ \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{( \frac{x}{10} - \frac{x}{15}) \times 100 }{ \frac{x}{15} } \\ \\ \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{ \frac{5x}{150} \times 100 }{ \frac{x}{15} } \\ \\ \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{500x \times 15}{150x} \\ \\ \: \: \: \: \: \: \: \: \: \: \: \: \: =50\%$