\(\sqrt{20} = \sqrt{4} ⋅ \sqrt{5} = 2 \sqrt{5} \text{.}\)

\(-3 \sqrt{8} = -3 ⋅ \sqrt{4} ⋅ \sqrt{2} = -3 ⋅ 2 ⋅ \sqrt{2} = -6 \sqrt{2} \text{.}\)

\(\sqrt{2\frac{14}{25}} = \sqrt{\frac{64}{25}} = {\sqrt{64} \over \sqrt{25}} = \frac{8}{5} = 1\frac{3}{5} \text{.}\)

\({18 \sqrt{140} \over 9 \sqrt{7}} = {18 \over 9} ⋅ {\sqrt{140} \over \sqrt{7}} = 2 \sqrt{20} = 2 ⋅ \sqrt{4} ⋅ \sqrt{5} = 2 ⋅ 2 ⋅ \sqrt{5} = 4 \sqrt{5}\)