$A$ shopkeeper sells one transistor for $Rs.\, 840$ at a gain of $20 \%$ and another for $Rs.\, 960$ at a loss of $4 \%$. His total gain or loss percent is

$20 \%$ loss on selling price is what per cent loss on the cost price? (in $\%$)

$A$ shopkeeper sold an article offering a discount of $24 \%$ and earned a profit of $23.5 \%$. What would have been the percentage of profit earned if no discount had been offered?

Surbhi bought a combined total of $25$ i-pads and i-phones. She marked up the i-pad by $20 \%$ on the cost price,while each i-phone was marked up by $Rs. 2000$. She was able to sell $75 \%$ of the i-pads and $2$ i-phones and make a profit of $Rs. 49000$. The remaining i-pads and $3$ i-phones could not be sold by her. Find her overall profit or loss if she gets no return on unsold items and it is known that an i-phone costs $50 \%$ of an i-pad.

By selling an article for $Rs. 102$,there is a loss of $15 \%$. When the article is sold for $Rs. 134.40$,the net result in the transaction is:

$A$ shopkeeper buys articles at $8$ for $Rs\,16$ and sells them at $9$ for $Rs\,20$. What is his gain or loss percent?