If the selling price of $40$ articles is equal to the cost price of $50$ articles,the loss or gain percent is

$A$ trader mixes three varieties of groundnuts costing $Rs. 50$,$Rs. 20$,and $Rs. 30$ per $kg$ in the ratio $2:4:3$ by weight and sells the mixture at $Rs. 33$ per $kg$. What is the percentage of profit he makes?

By selling an article for $Rs. 21$,a man incurs a loss such that the percentage loss is equal to the cost price. The cost price of the article is (in $Rs.$):

$A$ man bought apples at the rate of $6$ for $Rs. 20$ and sold them at $4$ for $Rs. 16$. His estimated profit $\%$ is

$X$ sells two articles for $Rs. 4,000$ each with no loss and no gain in the transaction. If one was sold at a gain of $25\%$, the other is sold at a loss of ........$\%$.

$A$ vendor buys bananas at $9$ for $Rs. 8$ and sells at $8$ for $Rs. 9$. What will be the profit or loss (in $\%$)?