The selling price of an article is of the cost price. The gain per cent is

Oranges are bought at 5 for Rs. 10 and sold at 6 for Rs.15. His gain per cent is

By selling a radio for Rs. 950, a man loses 5%. What per cent shall he gain by selling it for Rs. 1040?

On selling a chair forRs. 720, a man loses 25%. To gain 25% it must be sold for

The ratio of cost price and selling price of an article is 20 : 21. What is the gain per cent on it?