if (a + b) + c = d, then a + c = d - b

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• a + c = d - b,

  if the following are true:

  • a = c
  • b = c

  then a = b

  • d - b = d + (b ⋅ (-1)), a - b = a + (b ⋅ (-1))
  • a + c = d + (b ⋅ (-1)),

    if (a + b) + c = d, then a + c = d + (b ⋅ (-1))

    • (a + b) + c = d