A trader sold an article at a gain of $20 \%$. Had he purchased it for $40 \%$ more and sold for $Rs.\, 24$ less, he would have incurred a loss of $20 \%$. What is the cost price (in $Rs.$) of the article?

A shopkeeper sold an article for $Rs.\, 400$ after giving $20 \%$ discount on the labelled price and made $30 \%$ profit on the cost price. What would have been the percentage profit, had he not given the discount?

An $Ox$ and a carriage together cost $Rs.$ $8000$ The ox is sold at profit of $10 \%$ and carriage is sold at loss of $10 \% .$ If total profit made is $2.5 \%$ then what is the cost price of the $ox$? (in $Rs.$)

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 $30 \% ?$

A discount dealer professes to sell his goods at cost price but uses a weight of $960\, gms$ instead of a $Kg$ weight. Find his gain $\% ?$

Amit buys $5$ watches for $Rs.\, 9450$ and later sells them for $Rs\,.9700$ How much profit does Amit make per watch in $Rs.$?