A person sells $36$ apple per rupee and suffers a loss of $4 \% .$ Find how many apple per rupees to be sold to have a gain of $8 \%$.

A man purchased $150$ pens at the rate of $Rs.\, 12$ per pen. He sold 50 pens at gain of $10 \% .$ The percentage gain at which he must sell the remaining pens so as to gain $15 \%$ on the whole outlay is........$\%$

If the cost price of $21$ watches is equal to the selling price of $18$ pieces, then what would be the gain percent in this transaction?

Tarun bought a $TV$ with $20 \%$ discount on the labelled price. Had he bought it with $25 \%$ discount, he would have saved $Rs.\,500.$ At what price did he buy the $TV?$

By selling an article at $80 \%$ of its marked price, a shopkeeper makes a loss of $10 \% .$ What will be the profit percentage if he sells it at $95 \%$ of its marked price?

Nitin bought some oranges at $Rs.\, 40$ a dozen and an equal number at $\,30$ a dozen. He sold them at $Rs.\,45$ a dozen and made a profit of $\,480.$ The number of oranges, he bought, was