\[ 87 \frac{3}{70} - 19 \frac{1}{70} = (87 - 19) + \left(\frac{3}{70} - \frac{1}{70}\right) = 68 + \frac{2}{70} = 68 \frac{2}{70} = 68 \frac{1}{35} \]
Ответ: 68 1/35