If $50 \%$ of $(x-y) = 30 \%$ of $(x+y)$,then what percent of $x$ is $y$?

If $60 \%$ of the students in a school are boys and the number of girls is $812$,how many boys are there in the school?

The population of a variety of tiny bushes in an experimental field increased by $10 \%$ in the first year,increased by $8 \%$ in the second year,but decreased by $10 \%$ in the third year. If the present number of bushes in the experimental field is $26730$,then the number of bushes in the beginning was:

If one number is $80 \%$ of the other and $4$ times the sum of their squares is $656,$ then the numbers are:

The population of a town was $48600$. It increased by $25\%$ in the first year and decreased by $8\%$ in the second year. What will be the population of the town at the end of $2$ years?

For a rectangle,the length and breadth are increased by $10 \%$ and $20 \%$,respectively. The percentage increase in area is: