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

The price of an article is raised by $30 \%$ and then two successive discount of $10 \%$ each are allowed. Ultimately, the price of the article is

A person purchases $8$ pens for ₹ $10$ and sells $10$ pens for ₹ $8.$ How much profit or loss does he make in ?

By selling an article at $\frac{3}{4}^{t h}$ of the marked price, there is gain of $25 \%$. The ratio of the marked price and the cost price is

Articles are marked at a price which gives a profit of $25 \%$. After allowing a certain discount the profit reduces to $12\frac{1}{2} \%$. The discount percent is

A shopkeeper sells goods at $10 \%$ loss on cost price, but uses $20 \%$ less weight. What is his profit or loss percentage?