Calculate the following mathematical expressions.

Решение:

1. \[-10+(-20) = -30\]
2. \[-15+(-2,7) = -17,7\]
3. \[-3,4+(-6,6) = -10\]
4. \[-5,8+(-1,4) = -7,2\]
5. \[\frac{2}{5} + \left(-\frac{3}{5}\right) = \frac{2-3}{5} = -\frac{1}{5}\]
6. \[-15,6 + (-28,4) = -44\]
7. \[\frac{1}{3} + \left(-2\frac{1}{3}\right) = \frac{1}{3} - \frac{7}{3} = \frac{1-7}{3} = -\frac{6}{3} = -2\]
8. \[-15+27 = 12\]
9. \[-3+9 = 6\]
10. \[16-20 = -4\]
11. \[25-38 = -13\]
12. \[-1 + \frac{5}{14} = -\frac{14}{14} + \frac{5}{14} = -\frac{9}{14}\]
13. \[3,5 + (-5) = -1,5\]
14. \[4 + \left(-6\frac{1}{2}\right) = 4 - 6,5 = -2,5\]
15. \[2 - \frac{5}{8} = \frac{16}{8} - \frac{5}{8} = \frac{11}{8}\]
16. \[\frac{3}{4} - 1 = \frac{3}{4} - \frac{4}{4} = -\frac{1}{4}\]
17. \[-1 + \frac{3}{7} = -\frac{7}{7} + \frac{3}{7} = -\frac{4}{7}\]
18. \[-23+50 = 27\]
19. \[-71-45 = -116\]
20. \[23-50 = -27\]