$15 \%$ of $578 + 22.5 \%$ of $644 = ?$

$\frac{3}{4}$ of $\frac{2}{3}$ of $\frac{1}{5}$ of a number is $249.6$. What is $50\%$ of that number?

Two numbers are respectively $60 \%$ and $20 \%$ more than a third number. The second number expressed as a percentage of the first is:

In a class of $50$ students and $5$ teachers,each student received sweets equal to $12 \%$ of the total number of students,and each teacher received sweets equal to $20 \%$ of the total number of students. How many sweets were there in total?

If inflation increases at a rate of $8 \%$ p.a.,what will a $₹ 20$ article cost at the end of two years?

$40 \%$ are the passing marks. $A$ student gets $250$ marks yet fails by $38$ marks. What is the maximum marks?