A man deposited $50\%$ of the initial amount to his locker. And again after some time, he deposited $20\%$ of the increased amount. Now the amount becomes $\mathrm{Rs}.18000$. How much was the initial amount?

If the annual increase in the population of a town is $4\%$ and the present number of people is $15625$ what will be the population in $3$ years ?

If the annual decrease in the population of a town is $5\%$ and the present number of people is $40000$, what will be the population in $2$ years?

If the price is increased by $10\%$ and the sale is decreased by $5\%$, then what will be the effect on income?

If the price is decreased by $12\%$ and sale is increased by $10\%,$ then what will be the effect on income?

A student has to secure $40\%$ marks to get through. If he gets $40$ marks and fails by $40$ marks, find the maximum marks set for the examination.

If one of the sides of a rectangle is increased by $20\%$ and the other is increased by $5\%,$ find the percent value by which the area changes?

What quantity of water should be added to reduce $9$ liters of $50\%$ acidic liquid to $30\%$ acidic liquid?

When the price of radio was reduced by $20\%$, the sale increased by $80\%$. What was the net effect on sale ?