Question

a vegetable seller on selling 20kg potatoes earns a profit equal to the selling price of 5kg potatoes. find his profit percentage.

Answer 1

Let x be the C.P. of 1 kg of potatoes.
Thus, the C.P of 20kg of potatoes is 20x.
The profit in selling 20kg of potatoes is 5x.
Thus the profit is 5x. 
Profit%=Profit/CP*100%
=25%