$75 \%$ of $480 = x \times 15$. Find the value of $x$.

$15 \%$ of $10 \%$ of $20 \%$ of $1000$ is?

Ram borrowed $Rs. 725$ from Shyam at the beginning of a year at a certain rate of interest. After $8$ months,he again borrowed $Rs. 362.50$ at a rate of interest double that of the former sum. At the end of the year,the total interest on both loans is $Rs. 43.50$. Find the first rate of interest per annum.

The difference between a number and its two-fifth is $610$. What is $10\%$ of that number?

$860 \%$ of $50 + 50 \%$ of $860 = ?$

In an examination,$37 \frac{1}{2} \%$ of the candidates were girls. If $75 \%$ of the boys and $62 \frac{1}{2} \%$ of the girls passed,and $342$ girls failed,find the number of boys who failed.