4 5 1--= 9 9

1 4/9 - 5/9 = 8/9

$$1 \frac{4}{9} - \frac{5}{9} = \frac{1 \cdot 9 + 4}{9} - \frac{5}{9} = \frac{9+4}{9} - \frac{5}{9} = \frac{13}{9} - \frac{5}{9} = \frac{13-5}{9} = \frac{8}{9}$$

Ответ: $$\frac{8}{9}$$