1) -6 2/9 + 2 5/6 = - ⁵⁶/₉ + ¹⁷/₆ = -⁵⁶ˣ²/₁₈ + ¹⁷ˣ³/₁₈ = - ¹¹²/₁₈ + ⁵¹/₁₈ = - 2⁹/₁₈ = -2¹/₂
2) - 11/18 - (-16/27) = - ¹¹/₁₈ + ¹⁶/₂₇ = -¹¹ˣ³/₅₄ + ¹⁶ˣ²/₅₄ = -³³/₅₄ + ³²/₅₄ = -¹/₅₄
3) 5/9 - 2/3 = ⁵/₉ - ²ˣ³/₉ = ⁵⁻⁶/₉ = -¹/₉
4) 4,17 - 9,42 + 0,2 = -5,25 + 0,2 = - 5,05
5) - 18,31 - 6,27 + (- 8,44) - (-31,67) =2,55
- 18,31 - 6,27 = -24,59
-24,58 - 8,44 = - 33,02
-33,02 + 31,67 = 2,55
6) 6 5/12 - (- 4 2/3) + (- 2 3/4) = 6 5/12 + 4 2/3 - 2 3/4 = ⁷⁷/₁₂ + ¹⁴/₃ - ¹¹/₄ =
⁷⁷/₁₂ + ¹⁴ˣ⁴/₁₂ - ¹¹ˣ³/₁₂ = ⁷⁷/₁₂ + ⁵⁶/₁₂ - ³³/₁₂ = ⁷⁷⁺⁵⁶⁻³³/₁₂ = ¹³³⁻³³/₁₂ = ¹⁰⁰/₁₂ = 8⁴/₁₂ = 8¹/₃