AC = 3x - 1
AB = 4 x + 8
LINE: A—C—B
4x + 8 is the equation for the whole line, including BC. So you would just have to subtract 3x - 1, the equation for AC, from the equation for AB to find the equation for BC: 4x + 8
-3x - 1
So BC would equal x + 9, since the negative turns the “- 1” into a positive one.
