Выразим $$a$$:
$$a = \frac{7}{12} + 7\frac{5}{8}$$
$$a = \frac{7}{12} + \frac{61}{8} = \frac{7 \cdot 2}{12 \cdot 2} + \frac{61 \cdot 3}{8 \cdot 3} = \frac{14}{24} + \frac{183}{24} = \frac{197}{24} = 8\frac{5}{24}$$
Ответ: $$a = 8\frac{5}{24}$$