If selling price is doubled, profit triples. Find the profit percent.

A trader mixes $26\, kg$ of rice at $Rs.\, 20$ per $kg$ with $30\, kg$ of rice of another variety at $Rs.\, 36$ per $kg$ and sells the mixture at $Rs$ $30$ per $kg.$ His profit percent is

Sasha goes to a shop to buy a sofa set and a center table. Ske bargins for a $10 \%$ discount on the center table and and $25 \%$ discount on sofa set. However, the manager, by mistake, interchanged the discount percentage figures while making the bill and Sasha paid accordingly. When compared to what she should pay for her purchases, what percentage did Sasha pay extra given that the center table costs $40 \%$ as much as the sofa set.

A shopkeeper marks his goods at $40 \%$ above their cost price. He is able to sell $\frac{3}{4}$ th of his goods at this price, and the remaining at $40 \%$ discount. Assuming that the shopkeeper is able to sell the goods he buys, find his loss or gain as $\%$ of the whole transaction.

A shopkeeper sold an article for $Rs.\, 400$ after giving $20 \%$ discount on the labelled price and made $30 \%$ profit on the cost price. What would have been the percentage profit, had he not given the discount?