First we use the Additive Property of Equality to claim that:

a + 90 + -90 = 180 + -90

Then we show that:

1. left side reduces to a.
2. right side reduces to 90.

Quiz (1 point)

• 90 + (-90) = 0
• (a + b) + c = a + (b + c)
• a + 0 = a
• 180 + (-90) = 90

• if a = b, then a + c = b + c

• if 90 + (-90) = 0, then a + (90 + (-90)) = a + 0

• if the following are true:

  • a = b
  • b = c

  then a = c

• if the following are true:

  • a = b
  • b = c

  then a = c

• if the following are true:

  • a = b
  • a = c
  • b = d

  then c = d

Please write your proof in the table below. Each row should contain one claim. The last claim is the statement that you are trying to prove.

Step	Claim	Reason (optional)	Error Message (if any)
1
2
3
4
5
6
7
8
9
10

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