Question

If the selling price of 10 pens is equal to the cost price of 14 pens, find gain per cent.

Answer 1

Let the cost of each pen be Rs. 1
CP of 10 pens = Rs. 10
SP of 10 pens = CP of 14 pens = Rs. 14
Gain = SP - CP = 14-10= Rs. 4
$$\begin{gathered} \mathrm{Gain}\%=\left(\frac{\mathrm{Gain}}{\mathrm{CP}}\times 100\right)\% \\ =\left(\frac{4}{10}\times 100\right)\% \\ =40\% \end{gathered}$$