Respuesta :

mhanifa

Answer:

  • 156°

Step-by-step explanation:

∠3 is the exterior angle and:

  • m∠3 = m∠1 + m∠2

Substitute and solve for x

  • 7x + 9 = 3x + 13 + 3x + 17
  • 7x + 9 = 6x + 30
  • 7x - 6x = 30 - 9
  • x = 21

Find the measure of ∠3

  • m∠3 = 7*21 + 9 = 147 + 9 = 156°