Question

If the cost price of 25 books is equal to the selling price of 20 books, then find the gain/loss percentage per book?

• A. 50%
• B. 20%
• C. 25%
• D. 15%

Answer 1

The correct option is C 25%

Let's suppose cost price of 1 book is $x$.
$\Rightarrow$ Cost price of 25 books $=25\times x=25x$

Given that cost price of 25 books is equal to selling price of 20 books.
$\Rightarrow$ Selling price of 1 book $=\frac{25x}{20}=\frac{5x}{4}$

And, as we can see that selling price is more than cost price because,
$\frac{5x}{4}>x[x>0]$

$\Rightarrow$ Gain = $\frac{5x}{4}-x=\frac{x}{4}$
$\Rightarrow$ Gain percentage = $\frac{Gain}{CostPrice}\times 100\%=\frac{\frac{x}{4}}{x}\times 100\%\Rightarrow \frac{1}{4}\times 100\%=25\%$

Hence, option d is correct.