What percent of $12$ is $84$?

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

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:

What percent of Rs. $2650$ is Rs. $1987.50$?

Rajeev buys goods worth $₹ 6650$. He gets a rebate of $6 \%$ on it. After getting the rebate,he pays sales tax @ $10 \%$. Find the amount he will have to pay for the goods.

$6 \frac{1}{4} \%$ of $1600 + 12 \frac{1}{2} \%$ of $800$ equals