Evaluate $28 \%$ of $450 + 45 \%$ of $280$.

$405$ toffees were distributed equally among children in such a way that the number of toffees received by each child is $20 \%$ of the total number of children. How many toffees did each child get?

The population of a town was $160000$ three years ago. If it increased by $3 \%$,$2.5 \%$,and $5 \%$ respectively in the last three years,then the present population is:

The difference between a discount of $35 \%$ and two successive discounts of $20 \%$ and $20 \%$ on a certain bill was ₹ $22$. Find the amount of the bill.

$A$ number,when $35$ is subtracted from it,reduces to its $80$ percent. What is four-fifths of that number?

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 $\%$)?