The marked price of a chair is Rs. 800. A shopkeeper purchased it on two successive discounts of 10% and 15%. He spent Rs. 25 on transportation and sold the chair for Rs.800. Find out his gain / loss percentage.

Given: 

Marked Price = Rs. 800

Successive discounts =  10% and 15% respectively

Spend on transportation = 25

Selling price = Rs. 800

Calculation:

Cost price after successive discounts  

=  Marked price x \({100 - 10} \over 100\) x \({100 - 15} \over 100\)

Cost price after successive discounts = 800 x \(90 \over 100\) x \(85 \over 100\) 

= 612

He spends on transportation = Rs 25

so, Cost price =612 + 25 = 637

Selling price = Rs 800

Profit = SP - CP = 800 - 637

= 163

Percentage profit = \(Profit \over CP\) x 100 =  \(163 \over 637\) x 100

= 25.58%

∴Percentage profit =  25.58%