# If the Selling Price of 10 Pens is Equal to Cost Price of 14 Pens, Find the Gain Percent. - Mathematics

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

#### Solution

$\text { Let the cost price of one pen be Rs . C, and the selling price be Rs } . S$

$\text { Therefore,} 10S = 14C$

$C = \frac{10}{14}S$

$\text { However, the cost price is less than the selling price } .$

$S . P . = \left( \frac{100 + \text {profit %}}{100} \right)C . P$

$S = \left( \frac{100 +\text { profit % }}{100} \right)C$

$\frac{S}{C} = \left( \frac{100 + \text { profit % }}{100} \right)$

$\frac{14}{10} = \left( \frac{100 +\text { profit % }}{100} \right)$

$\frac{1400}{10} = 100 + \text { profit %}$

$140 - 100 = \text { profit % }$

$\text { Profit % }= 40$

$=\text { 40 % }$

$\text { Therefore, the required profit percent is 40 % }.$

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#### APPEARS IN

RD Sharma Class 8 Maths
Chapter 13 Proft, Loss, Discount and Value Added Tax (VAT)
Exercise 13.1 | Q 9 | Page 11