Christy donated $10 \%$ of his income to an orphanage and deposited $20 \%$ of the remainder in his bank. If he has now $Rs$ $7200$ left,what is his income?

In an examination,the percentage of students qualified to the number of students appeared from school $A$ is $70 \%$. In school $B$,the number of students appeared is $20 \%$ more than the students appeared from school $A$ and the number of students qualified from school $B$ is $50 \%$ more than the students qualified from school $A$. What is the percentage of students qualified to the number of students appeared from school $B$?

The monthly salary of Mr. Sachdev increases by $5 \%$,and as a result,his new annual salary becomes $₹ 15,120$. What was his earlier monthly salary (before the increase)?

$A, B, C$ are three students. $A$ got $18 \%$ more marks than $B$ and $12 \%$ less than $C$. If $B$ got $220$ marks,how many marks did $C$ get?

$A$ number,when $35$ is subtracted from it,reduces to its $80$ percent. What is four-fifths of that number?

$A$ jar contains $10$ red marbles and $30$ green ones. How many red marbles must be added to the jar so that $60 \%$ of the marbles will be red?