Решение:
- 1) \( \frac{1.8 + 1}{1.8 - 1} = \frac{2.8}{0.8} = \frac{28}{8} = \frac{7}{2} = 3.5 \)
- 2) \( \frac{1.5 + 1}{7.6 - 5} = \frac{2.5}{2.6} = \frac{25}{26} \)
- 3) \( \frac{23 - 15}{-5} = \frac{8}{-5} = -1.6 \)
- 4) \( \frac{19 - 13}{-7} = \frac{6}{-7} = -\frac{6}{7} \)
Ответ: 1) 3.5; 2) 25/26; 3) -1.6; 4) -6/7