$\frac{3}{4}$ of $\frac{2}{3}$ of $\frac{1}{5}$ of a number is $249.6$. What is $50\%$ of that number?

Ravi is $12$ years younger than Surya. Ravi's age is $40 \%$ of the sum of his and Surya's age. What will be Surya's age $9$ years hence?

Christy donated $10 \%$ of his income to an orphanage and deposited $20 \%$ of the remainder in his bank. If he has now $Rs$ $7200$ left,what is his income?

The population of a town increases $4 \%$ annually but is decreased by emigration annually to the extent of $(1/2) \%$. What will be the increase per cent in $3$ years?

$0.35 \%$ of a number is equivalent to multiplying it by the number:

In a school there are $1500$ students,$44 \%$ of whom are girls. The monthly fee of each boy is $₹ 540$ and the fee of each girl is $25 \%$ less than that of a boy. What is the sum of the monthly fees of all the boys and girls?