$A$ man buys an article for $10 \%$ less than its value and sells it for $10 \%$ more than its value. His gain or loss percent is

$A$ man buys $300$ dozen of bananas for $Rs. 3,600$. He sold $1/3$ of the stock at a loss of $10\%$ and the remaining $2/3$ of the stock at a gain of $10\%$. Find his overall percent profit or loss.

By selling an article for $Rs. 21$,a man incurs a loss such that the percentage loss is equal to the cost price. The cost price of the article is (in $Rs.$):

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 $12 \%$?

$A$ shopkeeper sold decks at $Rs. 166$ each after giving $17\%$ discount on the labelled price. Had he not given the discount,he would have earned a profit of $25\%$ on the cost price. What was the cost price of each deck? (in $Rs.$)

By what fraction selling price $(S.P.)$ must be multiplied to get the cost price $(C.P.)$ if the loss is $20 \%$?