A shopkeeper allows his customers 10% off on the marked price of goods and still gets a profit of 25%.
Question:

A shopkeeper allows his customers 10% off on the marked price of goods and still gets a profit of 25%. What is the actual cost to him of an article marked Rs 250?

Solution:

Let the CP of the article be Rs. $x$.

MP of the article $=$ Rs. 250

Discount $=10 \%$

Discount $=10 \%$ of 250

$=0.10 \times 250$

$=$ Rs. 25

SP $=$ MP $-$ Discount

$=250-25$

$=$ Rs. 225

Given,

Profit $=25 \%$

$\mathrm{CP}=\left[\frac{100}{(100+\text { Gain } \%)} \times \mathrm{SP}\right]$

$x=\left[\frac{100}{(100+25)} \times 225\right]$

$=\left[\frac{100}{125} \times 225\right]$

$=R s .180$

Thus, the CP of the article is Rs. 180 .