$A$ 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?

$A$ cab driver makes a profit of $20 \%$ on every trip when he carries $3$ passengers and the price of petrol is $Rs. 30$ a litre. Find the percentage profit for the same journey if he goes with four passengers per trip and the price of petrol reduces to $Rs. 24$ a litre? (in $\%$)
(Assume that revenue per passenger is the same in both the cases.)

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 $Rs.$)

$A$ shopkeeper sold one-third of his goods at a loss of $15 \%$. To get a profit of $10 \%$ on the whole transaction,he should sell the remaining articles at a profit of in $\%$?

The $CP$ of $19$ articles is equal to the selling price $(SP)$ of $15$ articles. What is the gain percentage?

On an article,the profit is $210 \%$ of the cost price. If the cost price increases by $40 \%$ but the selling price remains constant,approximately what percent of the selling price will be the profit?