if the following are true:

• a = ((b + c) + d) + e
• d + e = f

then a = (b + c) + f

Start from the conclusion and work back up the proof. Click the arrow to show the parents.

• a = (b + c) + f,

  if the following are true:

  • a = b + c
  • c = d

  then a = b + d

  • a = (b + c) + (d + e),

    if the following are true:

    • a = b
    • b = c

    then a = c

    • a = ((b + c) + d) + e
    • ((b + c) + d) + e = (b + c) + (d + e), (a + b) + c = a + (b + c)
  • d + e = f