о) 7$$\frac{4}{7}$$ - 5$$\frac{7}{9}$$ = 7$$\frac{36}{63}$$ - 5$$\frac{49}{63}$$ = 6$$\frac{99}{63}$$ - 5$$\frac{49}{63}$$ = 1$$\frac{50}{63}$$
Ответ: 1$$\frac{50}{63}$$