Question

How much per cent above the cost price should a shopkeeper mark his good so that after allowing a discount of 20%on the marked price he gain 21%.

Answer 1

%gain or loss = X + Y + (X×Y)/100

X is the percent above the cost so its sign has to be positive and Y is discount so its sign has to be negative.

Now because gain is to be 12%

Therefore

12 = X - 20 - (20×X)/100

=X - 20 - X/5

Or

12 + 20 = X - X/5, or

32 = 4X/5, or

32×5 =4X

Therefore, X = 40% (it is positive value).

So the good has to be marked 40% above the cost price to gain 12% after allowing the discount of 20%.