The price of rice has been increased by $20 \%$. By what per cent should Sanjay reduce the consumption of rice in the family so that the expenditure on rice remains the same as before the increase in the price of rice?

An army lost $10 \%$ of its men in war,$10 \%$ of the remaining due to diseases,and $10 \%$ of the rest were hurt. Thus,the strength was reduced to $729000$ active men. Find the original strength.

If the price of petrol is increased by $20 \%$,by what percentage should the consumption be decreased by the consumer,if the expenditure on petrol remains unchanged (in $\%$)?

Aman gave $40 \%$ of the amount he had to Rohan. Rohan in turn gave one-fourth of what he received from Aman to Sahil. After paying $₹ 200$ to the taxi driver out of the amount he got from Rohan,Sahil now has $₹ 600$ left with him. How much amount did Aman have?

The population of a town increases by $2.5 \%$ annually but decreases by $0.5 \%$ every year due to migration. What will be the net percentage increase in population after $2$ years (in $\%$)?

Ram borrowed $Rs. 725$ from Shyam at the beginning of a year at a certain rate of interest. After $8$ months,he again borrowed $Rs. 362.50$ at a rate of interest double that of the former sum. At the end of the year,the total interest on both loans is $Rs. 43.50$. Find the first rate of interest per annum.