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

In an examination,$34 \%$ of students failed in Mathematics and $42 \%$ failed in English. If $20 \%$ of the students failed in both the subjects,then the percentage of students who passed in both the subjects was:

$A$ number increased by $22 \frac{1}{2} \%$ gives $98$. The number is

If the price of apples goes down by $10 \%,$ find the percentage of increase that a family should effect in its consumption so as not to increase expenditure on this account.

Evaluate $28 \%$ of $450 + 45 \%$ of $280$.

If $75 \%$ of a number is added to $75$,the result is the number itself. The number is: