\[\sqrt{8m} - 0,2\sqrt{200m} + 3\sqrt{72m} =\]
\[= 2\sqrt{2m} - 0,2 \cdot 10\sqrt{2m} + 3 \cdot 6\sqrt{2m} =\]
\[= 2\sqrt{2m} - 2\sqrt{2m} + 18\sqrt{2m} =\]
\[= 18\sqrt{2m}\]