$A$ 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 $Rs.$)

The market price of an article is $Rs. 100$. If the article is sold at a discount of $10 \%$,then $35 \%$ profit is realized. How much loss or profit will be made if it is sold for $Rs. 30$ less than the market price?

Arun purchased $30 \, kg$ of wheat at the rate of $Rs. \, 11.50$ per $kg$ and $20 \, kg$ of wheat at the rate of $Rs. \, 14.25$ per $kg$. He mixed the two and sold the mixture. Approximately at what price per $kg$ should he sell the mixture to make $30 \%$ profit? (in $Rs.$)

$X$ 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 ........$\%$.

$A$ merchant advertises $10 \%$ off on the items bought from his store. The total discount obtained by a customer who bought a cooker worth $Rs. 650$,a heater worth $Rs. 500$,and a bag worth $Rs. 65$ is (in $Rs.$): (in $.50$)

$A$ man buys an article for $Rs. 27.50$ and sells it for $Rs. 28.60$. Find the gain percent. (in $\%$)