$A$ merchant buys $4000 \, kg$ of wheat,one-fifth of which he sells at a gain of $5 \%$,one-fourth at a gain of $10 \%$,one-half at a gain of $12 \%$,and the remainder at a gain of $16 \%$. If he had sold the whole at a gain of $11 \%$,he would have made $Rs. 72.80$ more. What was the cost price of the crop per $kg$? (in $Rs.$)

Sasha goes to a shop to buy a sofa set and a center table. She bargains for a $10 \%$ discount on the center table and a $25 \%$ discount on the sofa set. However,the manager,by mistake,interchanged the discount percentage figures while making the bill and Sasha paid accordingly. When compared to what she should have paid for her purchases,what percentage did Sasha pay extra,given that the center table costs $40 \%$ as much as the sofa set (in $\%$)?

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

By selling an article at $\frac{2}{5}$ of the marked price,there is a loss of $25 \%$. The ratio of the marked price and the cost price of the article is

$A$ man sells two houses at the rate of $Rs. 1.995$ Lakhs each. On one house he gains $20 \%$ and on the other he loses $20 \%$. His gain or loss per cent in the whole transaction is

$A$ dealer buys a table listed at $Rs. 600$ and gets successive discounts of $10\%$ and $20\%$. What is his profit or loss percent if he sells it at $Rs. 540$?