If the $CP$ of $13$ bats is $Rs.$ $390 .$ What is the price in $Rs.$ when it is sold at $10 \%$ loss?

A shopkeeper sold an article offering a discount of $5 \%$ and earned a profit of $23.5 \% .$ What would have been the percentage of profit earned if no discount was offered?

At a cost of $60$ paise per article, Sarika produces $750$ articles. She puts the selling price such that if only $600$ articles are sold, she would have made a profit of $40 \%$ on the outlay. However, $120$ articles got spoilt and she was able to sell $630$ articles at this price. Find her actual profit or loss percent as the percentage of total outlay assuming that the unsold articles are useless.

By Selling $80\, ball$ pens for $Rs.\, 140$, a retailer loses $30 \% .$ How many ball pens should he sell for $Rs.\,104$ so as to make a profit of $30 \% ?$

The difference between successive discounts of $40 \%$ followed by $30 \%$ and $45 \%$ followed by $20 \%$ on the marked price of an article is $Rs.\,12.$ The marked price of the article is (in $Rs.$)

If eggs are bought $12$ for $Rs.\, 10$ and sold at $10$ for $Rs.\, 12$. What is the gain or loss $\%.$