Find his gain per cent.

A book was bought for Rs 650 and sold with a profit of Rs 104. Find the gain per cent.

The CP of a pen is Rs 80. It is sold at Rs 100. Find the gain per cent.

By selling 130 cassettes,a man gains an amount equal to the selling price of 5 cassettes.Find the gain per cent.

A trader marks his goods at 40% above the cost price and allows a discount of 25%. What is his gain per cent ?

If a commission of 10% is given on the list price,the gain is 20% .Find the gain per cent, if the cornmission is increased to 20%.

A trader marks his goods at 30% above cost price and allows a discount of 10%. What is his gain per cent?