A.4 Which is better?

Angles

Lines r and s are parallel. Find the measure of 1.

m8 = 65°

Alex's "Supplementary Angle" Method
8 and 7 are supplementary, so 180° - 65° = 7.
7 and 5 are supplementary, so 180° - 115° = 5.
3 and 5 add to 180°, so
180° - 65° = 3.
3 and 1 are supplementary, so 180° - 115° = 1.
180° - 65° = 115°
180° − 115° = 65°
180° − 65° = 115°
180° − 115° = 65°
m1 = 65°