7. 23 -15

7. $$23 \frac{6}{19} - 15 \frac{16}{19} = (23-15) + (\frac{6}{19} - \frac{16}{19}) = 8 - \frac{10}{19} = 7 \frac{19}{19} - \frac{10}{19} = 7 \frac{9}{19}$$

Ответ: $$7 \frac{9}{19}$$