If $18 \%$ of a number is $720,$ then what is $81 \%$ of the same number?

Mr. Katial buys a house for ₹$100000$ and rents it out. He puts $12.5 \%$ of each month's rent aside for upkeep and repairs,pays ₹$325$ per year as taxes,and realizes a $5.5 \%$ annual return on his investment. Find the monthly rent.

The population of a city increases at the rate of $5 \%$ per annum. If the present population of the city is $3,70,440$,its population $3$ years ago was:

Ram scored $30 \%$ marks and failed by $15$ marks. Aditya scored $40 \%$ marks and obtained $35$ marks more than those required to pass. What is the pass percentage (in $\%$)?

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

In measuring the sides of a rectangle,one side is taken $10 \%$ in excess and the other $20 \%$ in deficit. Find the error per cent in area calculated from the measurement.