\(\sqrt{8} + \sqrt{32} = \sqrt{4} ⋅ \sqrt{2} + \sqrt{16} ⋅ \sqrt{2} = 2 \sqrt{2} + 4 \sqrt{2} \text{.}\)

\(2 \sqrt{2} + 4 \sqrt{2} = 6 \sqrt{2} \text{.}\)

\(\sqrt{112} = \sqrt{16} ⋅ \sqrt{7} = 4 \sqrt{7} \text{.}\)

\(6 \sqrt{80} = 6 ⋅ \sqrt{16} ⋅ \sqrt{5} = 6 ⋅ 4 ⋅ \sqrt{5} = 24 \sqrt{5} \text{.}\)

\(3 \sqrt{125} - 7 \sqrt{80} = 3 ⋅ \sqrt{25} ⋅ \sqrt{5} - 7 ⋅ \sqrt{16} ⋅ \sqrt{5} \text{.}\)

\(3 ⋅ 5 ⋅ \sqrt{5} - 7 ⋅ 4 ⋅ \sqrt{5} = 15 \sqrt{5} - 28 \sqrt{5} = -13 \sqrt{5} \text{.}\)

\(\sqrt{\frac{25}{49}} = {\sqrt{25} \over \sqrt{49}} = \frac{5}{7} \text{.}\)