34.15--1. 8

34. $$15 - 1\frac{7}{8} = 15 - \frac{15}{8} = \frac{15 \cdot 8}{8} - \frac{15}{8} = \frac{120}{8} - \frac{15}{8} = \frac{105}{8} = 13\frac{1}{8}$$

Ответ: $$13\frac{1}{8}$$