In a certain store,the profit is $320 \%$ of the cost. If the cost increases by $25 \%$ but the selling price remains constant,approximately what percentage of the selling price is the profit?

$A$ sells an article to $B$ at a gain of $20 \%$,$B$ sells it to $C$ at a gain of $10 \%$,and $C$ sells it to $D$ at a gain of $12 \frac{1}{2} \%$. If $D$ pays $Rs. 29.70$,what was the cost price for $A$? (in $Rs.$)

On an article,the profit is $210 \%$ of the cost price. If the cost price increases by $40 \%$ but the selling price remains constant,approximately what percent of the selling price will be the profit?

$A$ discount series of $10 \%$,$20 \%$,and $40 \%$ is equal to a single discount of.......$\%$

$A$ machine is sold at a profit of $15 \%$. Had it been sold for $Rs\, 540$ more,$24 \%$ would have been gained. Find the cost price.

$A$ tradesman gives $4 \%$ discount on the marked price and gives $1$ book free for buying every $15$ books and thus gains $35 \%$. The marked price is increased above the cost price by (approx.) (in $\%$).