By selling an article for $Rs. 450$,a man loses $10\%$. The gain or loss percent if he sells it for $Rs. 540$ is:

$A$ 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.)

$A$ shopkeeper sells one transistor for $Rs.\, 840$ at a gain of $20 \%$ and another for $Rs.\, 960$ at a loss of $4 \%$. His total gain or loss percent is

When a book is sold at its Marked Price,it gives a profit of $40 \%$. What percentage of profit or loss will occur if it is sold at half the Marked Price?

$A$ fruit seller sells $\frac{3}{5}$ th part of fruit at a profit of $10 \%$ and the remaining at a loss of $5 \%$. If the total profit is $Rs. 1500$,then what is the total cost price of the fruit in $Rs.$?

$A$ man loses $20 \frac{1}{2} \%$ of his money and after spending $80 \%$ of the remainder,he is left with $Rs. 159$. How much did he have at first? (in $Rs.$)