$5 \%$ of $(25 \%$ of $₹ 1600)$ is

$A$ boy found the answer for the question "subtract the sum of $\frac{1}{4}$ and $\frac{1}{5}$ from unity and express the answer in decimals" as $0.45$. The percentage of error in his answer was

If $₹ 2800$ is $\frac{2}{7}$ percent of the value of a house,the worth of the house (in $₹$) is

$A$'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?

Aditya's salary was increased by $40 \%$ and then decreased by $25 \%$. Find the net effect on Aditya's salary.

The population of a town increases by $12 \%$ during the first year and decreases by $10 \%$ during the second year. If the present population is $50400$,what was it $2$ years ago?