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 $Rs.$)

The marked price of a piano was $Rs. 15,000$. At the time of sale,there were successive discounts of $20\%$,$10\%$,and $10\%$ on it. The sale price was (in $Rs.$)

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

$A$ product when sold with $10 \%$ rebate on the listed price gave a profit of $Rs$ $70$. What was its cost price? (in $Rs$)

Ram sells an article to Girish at a gain of $20 \%$,Girish sells it to Sanjay at a gain of $10 \%$,and Sanjay sells it to Aditya at a gain of $12 \frac{1}{2} \%$. If Aditya pays $Rs. 59.40$,what did it cost Ram in $Rs.$?

The cost price of an article is $64 \%$ of the marked price. The gain percentage after allowing a discount of $12 \%$ on the marked price is........$\%$