The remote interior angles of a triangle are basically the two angles that do not share a vertex with and are opposite to the exterior angle.
5. ∠1 and ∠2 6. ∠2 and ∠3 7. ∠1 and ∠3
Because the exterior angle of a triangle is equal to the remote interior angles we can set up the following equations: 8. [tex]x + 80 = 105 \\ x = 105 - 80 \\ x = 25[/tex] 9. [tex]x + 72 = 135 \\ x = 135 - 72 \\ x = 63[/tex]