If $A$ and $B$ are in the ratio $4:5$ and the difference of their squares is $81,$ what is the value of $A?$

What will be the inverse ratio of $17: 19$?

Out of the number of qualified candidates from State $P$ in $2008,$ the respective ratio of male and female candidates is $11: 7.$ If the number of female qualified candidates from State $P$ in $2008$ is $126,$ what is the total number of qualified candidates (both male and female) from State $P$ in $2008?$

$10 \ yr$ before,the ratio of ages of $A$ and $B$ was $13: 17$. After $17 \ yr$ from now,the ratio of their ages will be $10: 11$. The present age of $B$ is (in $yr$):

The ratio of two numbers is $4:5$. If both numbers are increased by $4$,the ratio becomes $5:6$. What is the sum of the two numbers?

The ratio of incomes of $P$ and $Q$ is $3:4$ and the ratio of their expenditures is $2:3$. If at the end of the year,each saves ₹ $2000$,then the income of $P$ is (in ₹):