17. 4 + 5/8 + 3/4.

$$ 4 + \frac{5}{8} + \frac{3}{4} = 4 + \frac{5}{8} + \frac{3 \cdot 2}{4 \cdot 2} = 4 + \frac{5}{8} + \frac{6}{8} = 4 + \frac{11}{8} = 4 + 1 \frac{3}{8} = 5 \frac{3}{8} $$

Ответ: $$5 \frac{3}{8} $$