4. Вычислите: a) 4 2/3 : 4 9/10 - (4 1/2 - 3 5/7 * 5/12). б) 10 - 85 : 5.

4. Вычислите: a) \(4\frac{2}{3} : 4\frac{9}{10} - (4\frac{1}{2} - 3\frac{5}{7} \cdot \frac{5}{12}) = \frac{14}{3} : \frac{49}{10} - (\frac{9}{2} - \frac{26}{7} \cdot \frac{5}{12}) = \frac{14}{3} \cdot \frac{10}{49} - (\frac{9}{2} - \frac{26 \cdot 5}{7 \cdot 12}) = \frac{20}{21} - (\frac{9}{2} - \frac{13 \cdot 5}{7 \cdot 6}) = \frac{20}{21} - (\frac{9}{2} - \frac{65}{42}) = \frac{20}{21} - (\frac{189}{42} - \frac{65}{42}) = \frac{20}{21} - \frac{124}{42} = \frac{40}{42} - \frac{124}{42} = -\frac{84}{42} = -2\) б) \(10 - 85 : 5 = 10 - 17 = -7\)