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?

An article is sold at a discount of $20 \%$ on the marked price. In order to gain $60 \%$ on the marked price,at how much more percent of the discounted price should it be sold?

In an examination,$34 \%$ of students failed in Mathematics and $42 \%$ failed in English. If $20 \%$ of the students failed in both the subjects,then the percentage of students who passed in both the subjects was:

$6 \frac{1}{4} \%$ of $1600 + 12 \frac{1}{2} \%$ of $800$ equals

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.

$A$ number is increased by $20 \%$ and then decreased by $20 \%$. What is the final percentage change in the number?