If Rs. $2800$ is $\frac{2}{7}$ of the value of a house,what is the total worth of the house (in Rs.)?

The quantity of water needed to reduce $9 \ ml$ of shaving lotion containing $50 \%$ alcohol to a lotion containing $30 \%$ alcohol is: (in $ml$)

$20 \%$ of $30 \%$ of $20 \%$ of $₹ 850$ is:

$34.5 \% \text{ of } 1800 + 12.4 \% \text{ of } 1500 = (?)^3 + 78$

If $20 \%$ of $a = b$,then $b \%$ of $20$ is the same as: (in $\%$ of $a$)

If $12 \%$ of $x$ is equal to $6 \%$ of $y,$ then $18 \%$ of $x$ will be equal to how much per cent of $y$ ?