9)-=4/7 - 21/8

Ответ: -1 91/56

\(\frac{4}{7} - \frac{21}{8} = \frac{4 \cdot 8}{7 \cdot 8} - \frac{21 \cdot 7}{8 \cdot 7} = \frac{32}{56} - \frac{147}{56} = -\frac{115}{56} = -1 \frac{59}{56}\)

\(= -1 \frac{56}{56} - \frac{59}{56} = -1 - \frac{3}{56} = -1 \frac{3}{56}\)

Ответ: -1 3/56