\[\boxed{\mathbf{1.}\mathbf{79}\mathbf{.\ ОК\ ГДЗ - домашка\ на\ }5}\]
\[= \frac{7 + 15 + 8}{30}\ \ :\frac{49 - 28 - 20}{50} =\]
\[= \frac{30}{30}\ :\frac{1}{50} = 1 \cdot 50 = 50\]
\[= 39\ :\frac{9 + 4}{24} + \frac{9}{100} \cdot \frac{12 - 7}{18} =\]
\[= 39 \cdot \frac{24}{13} + \frac{9}{100} \cdot \frac{5}{18} =\]
\[= 3 \cdot 24 + \frac{1}{40} = 72\frac{1}{40}\]