While selling a watch,a shopkeeper gives a discount of $15 \%$. If he gives a discount of $20 \%$,he earns $Rs. 51$ less as profit. What is the original price of the watch? (in $Rs$)

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

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

$A$ shopkeeper purchased $150$ identical pieces of furniture at the rate of $Rs. 250$ each. He spent an amount of $Rs. 2500$ on packing. He fixed the price of each furniture at $Rs. 320$. However,he decided to give a discount of $5 \%$ on the labeled price. What is the percent profit earned by him (in $\%$)?

Mohan buys a watch for $Rs. 350$ and sells it for $Rs. 392$. Find out his percentage of profit.

The cost price of an article is $64 \%$ of the marked price. Calculate the gain percent after allowing a discount of $12 \%$.