Arun purchased $30\, kg$ of wheat at the rate of $Rs.\,11.50$ per $kg$ and $20\, kg$ of wheat at the rate of $Rs.\,14.25$ per $kg$. He mixed the two and sold the mixture. Approximately at what price per $kg$ should he sell the mixture to make $30 \%$ profit? (in $Rs.$)

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

An article is marked for sale at $Rs.$ $504 .$ The shopkeeper gives a discount of $5 \%$ on the sale price and still earns a profit of $20 \% .$ What could be the purchase price of the article? (in $Rs.$)

By selling $25$ $metres$ of cloth a trader gains the selling price of $5$ $metres$ of cloth. The gain of the trader in $\%$ is

A fruit-seller buys some oranges and by selling $40 \%$ of them he fealises the cost price of all the oranges. As the oranges being to grow over-ripe, he reduces the price and sells $80 \%$ of the remaining oranges at half the previous rate of profit. The rest of the oranges being rotten are thrown away. The overall percentage of profit is

A fruit vendor buys $10$ bananas for $Rs.\, 14$ and sells them at $12$ for $Rs.\,15$. Find his percentage gain or loss.