13 articles were bought for Rs. 5980 and sold for Rs 6656. How much was the approximate profit percentage per article?

A man buys 12 articles for Rs. 12 /- and sells them at the rate of Rs.1.25 per article. His gain percentage is: 

A tradesman marks his goods at 20 % above the cost price. He allows his customers a discount of 8% on marked price. Find out his profit percent.

A man sells an article at 5 % above its cost price. If he had bought it at 5 % less than what he had paid for it and sold it at Rs. 2 less, he would have gained 10 %. The cost price of the article is