Answer:
Step-by-step explanation:
All of the angles in a triangle add up to 180° So make an equation by adding up all the angles and set it equal to 180. (2x-18) + (3x - 12) + 40 = 180
Combine like terms.
5x -18 - 12 + 40 = 180. Add up all the constants (plain numbers with no x)
5x + 10 =180 Subtract 10 from both sides
5x = 170 Divide both sides by 5
x = 34
