First, we use distributive property:
-9x - 45 + 81 = 9x - 9
Then, combine like terms: -45 + 81
-9x + 36 = 9x - 9
Add 9 to both sides.
-9x + 45 = 9x
Add 9x to both sides
45 = 18x
Divide both sides by 18
2.5 = x
