The marked price of a watch was $Rs. 720$. $A$ man bought the same for $Rs. 550.80$ after getting two successive discounts,the first being $10 \%$. The second discount rate is.......$\%$

$A$ sold a pen to $B$ at a profit of $20\%,$ $B$ sold the same pen to $C$ for $Rs.\,75$ thereby making a profit of $25 \% .$ Find the price at which $A$ bought the pen? (in $Rs.$)

$A$ sells an article to $B$ at $15 \%$ profit. $B$ sells it to $C$ at $10 \%$ loss. If $C$ pays $₹ 517.50$ for it,then $A$ purchased it at:

$A$ dishonest dealer defrauds to the extent of $x \%$ in buying as well as selling his goods by using faulty weight. What will be the gain per cent on his outlay?

$A$ shopkeeper purchased $70$ $kg$ of potatoes for $Rs. 420$ and sold the whole lot at the rate of $Rs. 6.5$ per $kg$. What will be his gain percent?

$A$ 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?