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

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

The present population of a town is $26010$. It increases annually at the rate of $2\%$. What was the population of the town two years ago?

$20 \%$ of $30 \%$ of $20 \%$ of $₹ 850$ is:

The price of an article is Rs. $100$. Its price is increased by $10 \%$,and then again its price is increased by $10 \%$. What is the total increase in the price?

How many students passed in first class?
Statements:
$I$. $85 \%$ of the students who appeared in the examination have passed either in first class,second class,or pass class.
$II$. $750$ students have passed in second class.
$III$. The number of students who passed in pass class is $28 \%$ of those who passed in second class.