A wholesaler offers 20% off season discount to the retailer and still makes a profit of 15% . What is the actual cost to him of an article marked rupees 862.50

Given: 

A wholesaler offers 20% off season discount to the retailer and still makes a profit of 15%.

To do: 

We have to find the actual cost to him of an article marked rupees 862.50.

Solution:

MP $=Rs.\ 862.50$

Discount $ \%=20 \%$
Therefore,

$SP= MP \times \frac{(100- Discount \%}{100}$

$=862.5\times \frac{100-20}{100}$

$=862.5\times \frac{80}{100}$

$=862.5\times \frac{8}{10}$

$=86.25\times8$

$=690$
Gain $ \% =15 \%$

Therefore,

$CP=\frac{100\times SP}{100+gain \%}$
$=\frac{100\times690}{100+15}$
$=\frac{69000}{115}$

$=Rs.\ 600$

The actual cost is Rs. 600.