7. (5/12 + 1/8) * 3/8 =

7. $$(\frac{5}{12} + \frac{1}{8}) \cdot \frac{3}{8} = (\frac{5^{(2}}{12} + \frac{1^{(3}}{8}) \cdot \frac{3}{8} = (\frac{10}{24} + \frac{3}{24}) \cdot \frac{3}{8} = \frac{13}{24} \cdot \frac{3}{8} = \frac{13 \cdot 3}{24 \cdot 8} = \frac{13 \cdot 1}{8 \cdot 8} = \frac{13}{64}$$

Ответ: 13/64