Question

A shopkeeper marks his goods 25% above the cost price and allows a discount of 12% on them what percent does he gain

Answer 1

Let the cost price be Rs. 100.
then the mark up price which is 30% above the cost price,
Mark price = (100 + 30% of 100) = Rs. 130
Shopkeeper gives a discount of 10% on mark up price, then the 
Selling Price = (130 - 10% 0f 130) = Rs. 117.
Gain = 117-100 = Rs. 17
%gain = (17*100)/100 = 17%.

Answer 2

mp=25%CP +CP
LET CP=100
mp =25%100+100
mp=125
sp=(1-r/100)mp
sp=(1-12/100)125
sp=(88/100)125
sp=110
gain=sp - cp
gain=110-100
gain=10
g%=gain/CP*100
g%=10/100*100
g%=10%