The greatest number among $3^{50}, 4^{40}, 5^{30}$ and $6^{20}$ is

The product of two numbers is $120$. The sum of their squares is $289$. The sum of the two numbers is

In a college,$\frac{1}{5}$ of the girls and $\frac{1}{8}$ of the boys took part in a social camp. The fraction of the total students in the college who took part in the camp is:

$\left[ {8\left\{ {\left( {\frac{{21 \times \sqrt {\frac{9}{{441}}} }}{5} \text{ of } 60\% - \frac{1}{5}} \right) \times 625 + 7} \right\} \div 4} \right] = ?$

If the two digits of the age of Mr. Manoj are reversed,then the new age so obtained is the age of his wife. $\frac{1}{11}$ of the sum of their ages is equal to the difference between their ages. If Mr. Manoj is older than his wife,then find the difference between their ages.

$n$ is a whole number which when divided by $4$ gives the remainder $3$. The remainder when $2n$ is divided by $4$ is