By selling cloth at $Rs. 9$ per meter,a shopkeeper loses $10 \%$. Find the rate at which it should be sold so as to earn a profit of $15 \%$ (in $Rs.$).

$A$ man buys $10$ oranges for a rupee and sells $8$ oranges for a rupee. What is the profit percent?

$A$ man bought $15$ mangoes for a rupee. How many mangoes were sold for a rupee so that there is a loss of $25 \% ?$

$A$ wholesaler had $200$ dozens of mangoes. He sold some of these mangoes at $20 \%$ profit and the rest at $10 \%$ profit,so that he made $13 \%$ profit on selling all the mangoes. How many mangoes (in dozens) did he sell at $20 \%$ profit?

$A$ man sells two articles,each for $Rs. 640$. He earns $20\%$ profit on the first and $40\%$ profit on the second. Find his overall percent profit.

$A$ sold a horse to $B$ for $Rs. 4800$ by losing $20\%$. $B$ sells it to $C$ at a price which would have given $A$ a profit of $15\%$. $B$'s gain is (in $Rs.$)