Find the single discount equivalent to two successive discounts of $25\%$ and $15\%$.

 A shopkeeper marks his goods at $40\%$  above the cost price and offers a discount of $20\%$. What is his gain per cent?

A dealer purchases a water cooler for $₹3750$. He sells it after allowing a discount of $10\%$ on its marked price and gains $20\%$. Find the marked price of the water cooler.

The marked price of a washing machine is $₹15000$. A dealer allows two successive discounts of $20\%$ and $10\%$ on the marked price. How much I have to pay for the washing machine?

The marked price of a printer was $₹ 3525$ and it was sold at a discount of $20\%$. Find the discount allowed on the printer and also its selling price.

How much percent above the cost price should a shopkeeper mark his goods so that after allowing a discount of $10\%$on the marked price, he gains $8\%?$