Quiz (1 point)
Prove that:
(-9) + (9 + x) = x
The following properties may be helpful:
- ((-9) + 9) + x = x
- (a + b) + c = a + (b + c)
if the following are true:
- a = b
- a = c
then b = c
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.