4) (1 7).6 30+10)

4) $$(\frac{1}{30} + \frac{7}{10}) \cdot 6 = (\frac{1}{30} + \frac{7 \cdot 3}{10 \cdot 3}) \cdot 6 = (\frac{1}{30} + \frac{21}{30}) \cdot 6 = \frac{22}{30} \cdot 6 = \frac{11 \cdot 2}{5 \cdot 6} \cdot 6 = \frac{11}{5} = 2,2$$

Ответ: 2,2