4. Выполните действия: 1) 2.9+(-6,1); 3) -1-+ æ -+ 2)-5.4+12,2: 4) -6.7+6.7:6)3.8-6.3: 1 6 8 æ 30 80 5)8.5(-4.6): 7)-4,2-(-5): 8)--

1. 2.9 + (-6.1) = 2.9 - 6.1 = -3.2
2. -5.4 + 12.2 = 6.8
3. -\(\frac{1}{6}\) + \(\frac{1}{8}\) + \(\frac{30}{80}\) = -\(\frac{1}{6}\) + \(\frac{1}{8}\) + \(\frac{3}{8}\) = -\(\frac{1}{6}\) + \(\frac{4}{8}\) = -\(\frac{1}{6}\) + \(\frac{1}{2}\) = \(\frac{-1 + 3}{6}\) = \(\frac{2}{6}\) = \(\frac{1}{3}\)
4. -6.7 + 6.7 = 0; 0 : 6 = 0
5. 8.5 - (-4.6) = 8.5 + 4.6 = 13.1
6. 3.8 - 6.3 = -2.5
7. -4.2 - (-5) = -4.2 + 5 = 0.8
8. \(\frac{8}{15}\) - \(\frac{5}{6}\) = \(\frac{16}{30}\) - \(\frac{25}{30}\) = -\(\frac{9}{30}\) = -\(\frac{3}{10}\) = -0.3

Ответ: 1) -3.2; 2) 6.8; 3) \(\frac{1}{3}\); 4) 0; 5) 13.1; 6) -2.5; 7) 0.8; 8) -0.3