if the following are true:

• y = (a + b) / 2
• a = 0
• b = e

then y = e / 2

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

• y = e / 2,

  if the following are true:

  • a = b / c
  • b = d

  then a = d / c

  • y = (a + b) / 2
  • a + b = e,

    if the following are true:

    • a = 0
    • b = e

    then a + b = e

    • a = 0
    • b = e