By selling $100$ oranges,a vendor gains the selling price of $20$ oranges. His gain percent is

$A$ merchant advertises $10 \%$ off on the items bought from his store. The total discount obtained by a customer who bought a cooker worth $Rs. 650$,a heater worth $Rs. 500$,and a bag worth $Rs. 65$ is (in $Rs.$): (in $.50$)

Kunal bought a suitcase with $15 \%$ discount on the labelled price. He sold the suitcase for $Rs. 2880$ with $20 \%$ profit on the labelled price. At what price did he buy the suitcase? (in $Rs.$)

$A$ person earns $15 \%$ on an investment but loses $10 \%$ on another investment. If the ratio of the two investments is $3:5$,what is the gain or loss percentage on the two investments taken together (in $\%$)?

An $Ox$ and a carriage together cost $Rs. 8000$. The ox is sold at a profit of $10\%$ and the carriage is sold at a loss of $10\%$. If the total profit made is $2.5\%$,then what is the cost price of the ox? (in $Rs.$)

$A$ reduction of $10 \%$ in the price of rice enables a person to obtain $25 \text{ kg}$ more for $Rs. 2250$. Find the reduced price per $\text{kg}$ of the rice (in $Rs.$).