If the $CP$ of $13$ bats is $Rs. 390$,what is the selling price in $Rs.$ when it is sold at a $10 \%$ loss?

$A$ shopkeeper mixes $20 \, kg$ of rice which cost him $Rs. \, 5$ per $kg$ with $35 \, kg$ of rice which cost him $Rs. \, 7$ per $kg$. Then he sells the mixture at $Rs. \, 6.5$ per $kg$. Find his total profit and percent profit.

$A$ sells his house worth $Rs. 10\, lakh$ to $B$ at a loss of $10\%$. Later,$B$ sells it back to $A$ at $10\%$ profit. The result of the two transactions is:

$A$ fruit vendor buys $10$ bananas for $Rs. 14$ and sells them at $12$ for $Rs. 15$. Find his percentage gain or loss.

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 $10\%$. What was the second discount rate? (in $\%$)

The cost price of an article is $80 \%$ of its marked price for sale. How much percent does the tradesman gain after allowing a discount of $12 \%$?