$A$ 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 $\%$)?

$A$ shopkeeper listed the price of goods at $30 \%$ above the cost price. He sells half the stock at this price, one-fourth of the stock at a discount of $15 \%$, and the remaining at $30 \%$ discount. His overall profit is.......$\%$

Abhishek makes a profit of $Rs. 110$ if he sells a certain number of pens at the price of $Rs. 2.5$ per pen and incurs a loss of $Rs. 55$ if he sells the same number of pens for $Rs. 1.75$ per pen. How many pens does Abhishek have?

$A$ trader allows a trade discount of $20 \%$ and a cash discount of $6 \frac{1}{4} \%$ on the marked price of the goods and gets a net gain of $20 \%$ of the cost. By how much above the cost should the goods be marked for the sale? (in $\%$)

By selling an article at $\frac{2}{5}$ of the marked price,there is a loss of $25 \%$. The ratio of the marked price and the cost price of the article is

By selling a book for $Rs. 360$,$20\%$ profit was earned. What is the $CP$ of the book in $Rs.$?