$A$ vendor bought toffees at $6$ for a rupee. How many for a rupee must he sell to gain $20 \%$?

The cost price of $100$ books is equal to the selling price of $60$ books. The gain percentage or loss percentage is:

Vijay sold a watch at a gain of $5 \%$. Had he sold it for $Rs. 72$ more,he would have gained $13 \%$. Find out the cost price of the watch (in $Rs.$).

If $11$ mangoes are bought for $Rs. 10$ and sold at $10$ for $Rs. 11$,what is the gain or loss percentage (in $\%$)?

The profit earned by selling an article for $Rs. 832$ is equal to the loss incurred when the same article is sold for $Rs. 448$. What should be the selling price for making $50\%$ profit? (in $Rs.$)

$A$ man had a certain amount with him. He spent $20\%$ of that to buy an article and $5\%$ of the remaining on transport. Then he gifted $Rs. 120$. If he is left with $Rs. 1,400$,the amount he spent on transport is (in $Rs.$)