Question

A boy bought a book for $₹x$ and sold it for ₹ 25. If his loss percent equals $x,$ then the cost price of the book is .

• A. ₹40
• B. ₹50
• C. ₹60

Answer 1

The correct option is B ₹50

Given, C.P. = Loss % = $₹x$ and
S.P.=₹ 25.
​$\text{Loss \%}=\frac{C.P.-S.P.}{C.P.}\times 100$
$\Rightarrow x=\frac{x-25}{x}\times 100$

$\Rightarrow x^2=100x-2500$

$\Rightarrow x^2-100x+2500=0$

i.e., $x^2-50x-50x+2500=0$

$\Rightarrow x(x-50)-50(x-50)=0$

$\Rightarrow (x-50{)}^2=0$

i.e., The equation has equal roots.

Hence, the cost price of the book is $₹50.$