A man bought orange at the rate of $8$ for $Rs.\,34$ and sold them at the rate of $12$ for $Rs.\,57.$ How many oranges should be sold to earn a net profit of $Rs.\,45?$

Charging $30 \%$ above its production cost a radio maker puts a label of $Rs.\, 286$ on a ratio as its price. But at the time of selling it, he allows $10 \%$ discount on the labeled price. What will his gain be? (in $Rs.$)

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 cost price is $Rs.\, 150$ less than the selling price and profit is $20 \%,$ then what is the selling price (in $Rs.$)?

A shopkeeper purchased a chair marked at $RS.\, 600$ at two successive discounts of $15 \%$ and $20 \% .$ He spent $Rs.\, 28$ on transportation and sold the chair for $Rs.\,545.$ His gain percent was

If the cost price of $12$ pens is equal to selling price of $8$ pens, find the gain percent.