$A$ shopkeeper purchased $70$ $kg$ of potatoes for $Rs. 420$ and sold the whole lot at the rate of $Rs. 6.5$ per $kg$. What will be his gain percent?

$A$ trader sells rice at a profit of $5 \%$ and uses a weight which is $25 \%$ less. Find the total percentage gain.

$A$ dealer fixed the price of an article $40 \%$ above the cost of production. While selling it,he allows a discount of $20 \%$ and makes a profit of $Rs. 48$. The cost of production (in $Rs.$) of the article is:

The cost price of $100$ books is equal to the selling price of $60$ books. The gain percentage or loss percentage is:

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:

$A$ trader mixes $26 \text{ kg}$ of rice at $Rs. 20$ per $\text{kg}$ with $30 \text{ kg}$ of rice of another variety at $Rs. 36$ per $\text{kg}$ and sells the mixture at $Rs. 30$ per $\text{kg}$. His profit percent is: