The value of a machine depreciates at the rate of $10 \%$ every year. It was purchased $3$ years ago. If its present value is $₹ 8748$,what was its purchase price?

An empty fuel tank of a car was filled with an ordinary type of petrol. When the tank was one-third empty,it was filled with high-speed petrol. Again,when the tank was one-third empty,it was filled with an ordinary type of petrol. Again,when the tank was one-third empty,it was filled with high-speed petrol. At this time,what was the percentage of high-speed petrol in the tank?

If $x$ is $90 \%$ of $y,$ then what per cent of $x$ is $y$?

Mr. Shamin's salary increases every year by $10 \%$ in June. If there is no other increase or reduction in the salary and his salary in June $2011$ was $Rs$ $22,385$,what was his salary in June $2009$?

If $25 \%$ of a number is $6$,what is the number that is $50 \%$ more than the initial number?

After giving a $25 \%$ discount on the entry ticket,the number of visitors increased by $30 \%$. What will be the impact on the total revenue from entry tickets compared to other days?