A.4 Which is better?

Angles

Lines r and s are parallel. Find the measure of ∠2.

m∠7 = 65°
Alex's "Supplementary Angle" Method
∠7 and ∠5 are supplementary, so 180° - 65° = ∠5.
∠5 and ∠3
add to 180°, so
180° - 115° = ∠3.
∠3 and ∠1 are supplementary, so
180° - 65° = ∠1.
∠1 and ∠2 are supplementary, so 180° - 115° = ∠2.
180° - 65° = 115°
180° − 115° = 65°
180° − 65° = 115°
180° − 115° = 65°
m∠2 = 65°