Ответ:

  1. −18,25 + 3,5 = −14,75.
  2. −31,17 + 20 = −11,17.
  3. −54,8 + 43,1 = −11,7.
  4. −9,05 + 8,9 = −0,15.
  5. −0,06 + 1,1 = 1,04.
  6. −18,2 + 3,9 = −14,3.
  7. \( -\frac{23}{45}+\frac{1}{180}=-\frac{92}{180}+\frac{1}{180}=\mathbf{-\frac{91}{180}} \).
  8. \( -\frac{2}{39}+\frac{3}{78}=-\frac{4}{78}+\frac{3}{78}=\mathbf{-\frac{1}{78}} \).
  9. \( -5\frac{7}{18}+1\frac{4}{45}=-\frac{97}{18}+\frac{49}{45}=\mathbf{-4,3} \).
  10. \( -0,25+4\frac{1}{11}=-\frac14+\frac{45}{11}=\mathbf{3\frac{37}{44}} \).
  11. \( -3,125+2\frac78=-\frac{25}{8}+\frac{23}{8}=\mathbf{-\frac14} \).
  12. \( -14,37+2\frac{1}{50}=-14,37+2,02=\mathbf{-12,35} \).