9 15 9. 5--4-

9. $$5\frac{9}{23} - 4\frac{15}{23} = (5-4) + (\frac{9}{23} - \frac{15}{23}) = 1 - \frac{6}{23} = \frac{23}{23} - \frac{6}{23} = \frac{17}{23}$$
Ответ: $$\frac{17}{23}$$