5. Сократить дробь: a) 14/63 б) 32/80 в) 72/108 г) 25/40

a)

$$\frac{14}{63} = \frac{2 \cdot 7}{9 \cdot 7} = \frac{2}{9}$$

б)

$$\frac{32}{80} = \frac{4 \cdot 8}{10 \cdot 8} = \frac{4}{10} = \frac{2 \cdot 2}{5 \cdot 2} = \frac{2}{5}$$

в)

$$\frac{72}{108} = \frac{2 \cdot 36}{3 \cdot 36} = \frac{2}{3}$$

г)

$$\frac{25}{40} = \frac{5 \cdot 5}{8 \cdot 5} = \frac{5}{8}$$