By selling an A.C for Rs 18000, I loose 20%. What did I pay for it?

By selling a radio for Rs.240, I lose 20%. What percent shall I gain by selling it for Rs.320?

By selling 90 pens for Rs. 80 a man loses 20%. What should be the selling price (in Rs.) of 90 pens for 20% profit?

By selling an article for Rs.600 a man losses 20%. At what price should he sell it in order to gain 25%?

A buys an article for Rs. 650 and sells it to B at a profit of 20%. B sells it to Cat a loss of 20%. What does C pay for it?