A tradesman marked his goods at 26% above its cost price and then allowed a discount of 13%. His gain (in %) is:

Let the Cost Price (CP) be 100.
The markup is 26% above CP:

Marked Price (MP)=100+26=126
A discount of 13% is given on the MP:

Discount=13% of 126=
100
13×126
​
=
100
1638
​
=16.38
Selling Price (SP)=MP−Discount=126−16.38=109.62
Gain=SP−CP=109.62−100=9.62
Gain Percentage=
100
9.62
​
×100=9.62%
Alternatively, using the successive percentage formula a+b+
100
ab
​
where a=+26 and b=−13:

Net Gain%=26−13−
100
26×13
​
=13−3.38=9.62%