The mean proportional between $64$ and $81$ is

The difference between a two-digit number and the number obtained by interchanging the digits is $36$. What is the difference between the sum and the difference of the digits of the number if the ratio between the digits of the number is $1:2$?

₹ $1980$ is divided among $A$,$B$,and $C$ such that half of $A$'s part,one-third of $B$'s part,and one-sixth of $C$'s part are equal. What is $B$'s part (in ₹)?

If $\frac{A}{3} = \frac{B}{2} = \frac{C}{5},$ then what is the value of the ratio $(C+A)^{2} : (A+B)^{2} : (B+C)^{2} ?$

Two numbers are in the ratio $1: 2$. If $7$ is added to both,their ratio changes to $3: 5$. The greatest number is

The ratio of the present ages of Suresh and Mahesh is $7:5$. If after $6$ years their ages will be in the ratio of $4:3$,the present age of Mahesh is (in $years$):