Answer:
5x + 4 + x - 2 + 3x + 7 = 180° (red)
Step-by-step explanation:
All angles in a straight line adds up to 180°
Hence:
(5x + 4) + (x - 2) + (3x + 7) = 180°
5x + 4 + x - 2 + 3x + 7 = 180°
If you collect the like terms:
9x + 9 = 180° (this is not an option, so it must be the last one)
