$A$ 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 $\%$)?

$A$ 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 purchased $120$ reams of paper at $Rs. 80$ per ream. He spent $Rs. 280$ on transportation,paid octroi at the rate of $40$ paise per ream,and paid $Rs. 72$ to a porter. In order to gain $8\%$ profit,he must sell each ream of paper for (in $Rs.$):

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

$A$ cash payment that will settle a bill for $250$ chairs at $Rs. 50$ per chair less $20 \%$,$15 \%$,and a further discount of $5 \%$ on cash payment is (in $Rs.$):

$A$ shopkeeper marks his goods at $40 \%$ above their cost price. He is able to sell $\frac{3}{4}$ of his goods at this price,and the remaining at $40 \%$ discount. Assuming that the shopkeeper is able to sell all the goods he buys,find his overall gain or loss percentage.