Every real number is either rational or irrational.

$\pi$ is irrational and $\frac{22}{7}$ is rational.

$\left(2\sqrt{3}-5\sqrt{2}\right)+$$\left(\sqrt{3}+2\sqrt{2}\right)=a(\sqrt{b}-\sqrt{c})$. Find the value of $a$

$\left(2\sqrt{2} + 5\sqrt{3}-7\sqrt{5}\right)+$ $\left(3\sqrt{3}-\sqrt{2}+\sqrt{5}\right)=\sqrt{x}+a\sqrt{y}-b\sqrt{z}$. Find the value of $a-b$

If $\left(\frac{2}{3}\sqrt{7}-\frac{1}{2}\sqrt{2}+6\sqrt{11}\right)$  $+\left(\frac{1}{3}\sqrt{7}+\frac{3}{2}\sqrt{2}-\sqrt{11}\right)=\sqrt{a}+\sqrt{b}+c\sqrt{d}$. Find the value of $c$.

Multiply $3\sqrt{5}$ by $2\sqrt{5}$.

If $6\sqrt{15}\times 4\sqrt{3}=k\sqrt{5}$, find $k$.

If $2\sqrt{6}\times 3\sqrt{3}=k\sqrt{2}$, then find $k$.

Multiply:

$3\sqrt{8}$ by $3\sqrt{2}$