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 $12 \%$?

$A$ 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

Hemant purchased $120$ rims of paper at $Rs. 80$ per rim. He spent $Rs. 280$ on transportation,paid octroi at the rate of $40$ paise per rim,and paid $Rs. 72$ to the coolie. If he wants to have a gain of $8 \%$,the selling price per rim must be (in $Rs.$)

The cost price of $6$ pens is equal to the selling price of $4$ pens. Find the profit percent. (in $\%$)

$A$ shopkeeper professes to sell his goods at cost price but uses a weight of $800 \text{ g}$ instead of a $1 \text{ kg}$ weight. His profit percentage is:

Mr. Kapur purchased two toy cycles for $Rs. 750$ each. He sold these cycles,gaining $6 \%$ on one and losing $4 \%$ on the other. The gain or loss percent in the whole transaction is