$A$ person's salary has increased from $Rs. 7200$ to $Rs. 8100$. What is the percentage increase in his salary (in $\%$)?

$A$'s salary is $40 \%$ of $B$'s salary,which is $25 \%$ of $C$'s salary. What percentage of $C$'s salary is $A$'s salary?

The product of one-third of a number and $150 \%$ of another number is what percent of the product of the original numbers?

Suman's project report on 'Development with dignity',consists of $25$ pages,each with $60$ lines and $75$ characters per line. If the number of lines is reduced to $55$ but the number of characters per line is increased to $90$,what is the percentage change in the number of pages? (Assume the number of pages to be a whole number.)

In two successive years,$80$ and $60$ students of a school appeared at the final examination,of which $60 \%$ and $80 \%$ passed respectively. The average rate of students passed (in percent) is

$32.05 \% \text{ of } 259.99 = ?$