What is the value of $9 \frac{1}{3} + 19 \frac{2}{3} + 20 \frac{3}{4} + 19 \frac{1}{4}$?

On simplification of $\frac{(2.644)^{2}-(2.356)^{2}}{0.288},$ we get

In an examination,a student was asked to find $\frac{3}{14}$ of a certain number. By mistake,he found $\frac{3}{4}$ of it. His answer was $150$ more than the correct answer. The given number is

$108 \div ?$ of $\frac{1}{3} + \frac{2}{5} \times 3 \frac{3}{4} = 10 \frac{1}{2}$

If $\sqrt{x} - \sqrt{y} = 1$ and $\sqrt{x} + \sqrt{y} = 17$,then $\sqrt{xy} = ?$

If $a^{2}+b^{2}+c^{2}=2(a-b-c)-3,$ then the value of $(a-b+c)$ is