The cost price of $40$ articles is the same as the selling price of $25$ articles. Find the gain percent. (in $\%$)

Find $CP$ when $SP = Rs. 40.60$ and $\text{gain} = 16\%$.

$A$ shopkeeper sells an article at a gain of $10 \%$. Had he sold it at a loss of $20 \%$,its selling price would have been $Rs. 180$ less. What is the cost price of the article? (in $Rs.$)

$A$ man sold his two cars for $Rs. 4.5$ lakh each. In the sale of the first car, he incurred $20\%$ profit, and in the sale of the second, he incurred $20\%$ loss. What is the total amount of profit or loss?

The value of an article depreciates every year at the rate of $10 \%$ of its value. If the present value of the article is $Rs. 729$,then its worth $3$ years ago was (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: