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

$A$ discount of $40 \%$ on the marked price of a trouser enables Ajit to purchase a shirt also which costs him $₹ 320$. How much did Ajit pay for the trouser? (in $₹$)

$X$ sells two articles for $Rs. 4,000$ each with no loss and no gain in the transaction. If one was sold at a gain of $25\%$, the other is sold at a loss of ........$\%$.

Find $SP$ when $CP = Rs. 56.25$ and $\text{Gain} = 20\%$?

$A$ shopkeeper purchased a chair marked at $₹ 600$ at two successive discounts of $15 \%$ and $20 \%$. He spent $₹ 28$ on transportation and sold the chair for $₹ 545$. His gain percent was: (in $\%$)

$A$ shopkeeper sold chairs at $Rs. 2139$ each after giving a $7 \%$ discount on the labelled price. Had he not given the discount, he would have earned a profit of $15 \%$ on the cost price. What was the cost price of each chair? (in $Rs.$)