Selling price of 10 pens = cost price of 14 pens
Let cost price of 1 pen = Rs. x
Selling price of 10 pens = Rs. 14x
Selling price of 1 pen =Rs. \(\frac{14x}{10}\)
Gain = \(\frac{14x}{10}\) - x = \(\frac{4x}{10}\)
= \(\frac{SP}{CP}\) = \(\frac{14}{10}\) ... ... (i)
= Gain% = \(\frac{gain}{cost\,price}\)x 100 = \(\frac{\frac{4x}{10}}{x}\)x 100 = \(\frac{2}{5}\) x 100 = 40%
