$A$ student has to secure $15\%$ marks to pass the examination. If he gets $80$ marks and fails by $70$ marks,find the maximum marks set for the examination.

The first and second numbers are less than a third number by $30 \%$ and $37 \%$,respectively. The second number is less than the first by: (in $\%$)

From a container having pure milk,$20 \%$ is replaced by water and the process is repeated thrice. At the end of the third operation,the milk is: (in $\%$ pure)

In an election between two candidates,one got $55 \%$ of the total valid votes,and $20 \%$ of the total votes were invalid. If the total number of votes was $7500$,what was the number of valid votes that the other candidate received?

If $37 \frac{1}{2} \%$ of a number is $45,$ then $87 \frac{1}{2} \%$ of the number will be:

An $HR$ Company employs $4800$ people,out of which $45 \%$ are males and $60 \%$ of the males are either $25$ years or older. How many males are employed in the company who are younger than $25$ years?