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 $Rs.$)

A man buys $300$ dozen of bananas for $Rs.\, 3,600$. He sold $1 / 3^{rd}$ of the stock at a loss of $10 \%$ and the remaining $2 / 3^{rd}$ stock at a gain of $10 \% .$ Find his overall percent profit or loss.

Tarun bought a $TV$ with $20 \%$ discount on the labelled price. Had he bought it with $25 \%$ discount, he would have saved $Rs.\,500.$ At what price did he buy the $TV?$

A dealer marks his goods $30 \%$ above his cost price and then allows $15 \%$ discount on it. What is the cost price of an article on which he gains $Rs.\,84?$

On selling an article for $Rs.\, 170,$ a shopkeeper loses $15 \% .$ In order to gain $20 \%,$ he must sell that article at rupees

A dealer fixed the price of an article $40 \%$ above the cost of production. While selling it he allows a discount of $20 \%$ and makes a profit of $Rs.\, 48$. The cost of production (in $Rs.$) of the article is