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

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.

In a certain school,$20 \%$ of students are below $8$ years of age. The number of students above $8$ years of age is $\frac{2}{3}$ of the number of students of $8$ years age,which is $48$. What is the total number of students in the school?

On decreasing the price of a colour $TV$ by $30 \%$,its sale is increased by $20 \%$. The effect on the revenue is:

If in an examination $20 \%$ students failed in Hindi,$25 \%$ failed in English,and $7 \%$ failed in both subjects,then what is the percentage of students who failed in at least one of the subjects (in $\%$)?

$A$ batsman scored $110$ runs which included $3$ boundaries and $8$ sixes. What percent of his total score did he make by running between the wickets?