12. Each section of the line on each side is identical (shown by the marks through each line)
This means both those angles are also the same.
6x + 1 = 9x-23
Add 23 to both sides
6x + 24 = 9x
Subtract 6x from both sides
24 = 3x
Divide both sides by 3
X = 8
13. Both angles when added together need to equal 180
5x-24 + 8x +9 = 180
Combine like terms
13x -15 = 180
Add 15 to both sides
13x = 195
Divide both sides by 13
X = 15
