On selling $17$ balls at $₹720,$ there is a loss equal to the cost price of $5$ balls. The cost price of a ball is

Kunal bought a suitcase with $15 \%$ discount on the labelled price. He sold the suitcase for $Rs. 2880$ with $20 \%$ profit on the labelled price. At what price did he buy the suitcase? (in $Rs.$)

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

If the cost price of $21$ watches is equal to the selling price of $18$ watches,then what would be the gain percent in this transaction?

$A$ shopkeeper sold an article at the rate of $Rs. 35$ per article and earned a profit of $40\%$. At what price should each article have been sold to earn a profit of $60\%$?

$A$ man buys $10$ articles for $Rs. 8$ and sells them at $Rs. 1.25$ per article. His gain percent is