The population of a city is $20000$. It increased by $20\%$ during the first year and $30\%$ during the second year. The population after two years will be:

$A$ man spends $75 \%$ of his income. His income increases by $20 \%$ and his expenditure also increases by $10 \%$. The percentage of increase in his savings is (in $\%$)

$A$ student multiplied a number by $\frac{3}{5}$ instead of $\frac{5}{3}$. What is the percentage error in the calculation?

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?

On a test consisting of $150$ questions,Rita answered $40 \%$ of the first $75$ questions correctly. What per cent of the other $75$ questions does she need to answer correctly for her grade on the entire exam to be $60 \%$?

In the last financial year,a car company sold $41,800$ cars. In this year,the target is to sell $51,300$ cars. By what percent must the sale be increased?