Milk contains $5 \%$ water. What quantity of pure milk should be added to $10$ litres of milk to reduce this to $2 \%$?

If $8 \%$ of the people eligible to vote are between $18$ and $21$ years of age,and in an election,$85 \%$ of those eligible to vote who were between $18$ and $21$ years of age actually voted,then the number of persons between $18$ and $21$ years of age who actually voted is what percent of the total people eligible to vote?

If $X = 600$ and $Y = 800$,then $X$ is how much percent less than $Y$?

Peter could save $10 \%$ of his income. But two years later,when his income increased by $20 \%$,he could save the same amount as before. By what percentage has his expenditure increased?

Starting with $8000$ workers,the company increases the number of workers by $5 \%$,$10 \%$,and $20 \%$ at the end of the first,second,and third year,respectively. The number of workers in the fourth year is:

$45 \%$ of $1500 + 35 \%$ of $1700 = ? \%$ of $3175$