Answer:
PROOF FOR THE "PROVE" SECTION:
As linear pairs, angle 2 and 3 are supplementary to each other. Angle 1 is equal to angle 2, as they are both same-side interior angles. Therefore, angle 1 and angle 3 are also supplementary.
Filling in the missing blanks:
S1. Angle 1, Angle 2, Angle 3
S2. Angle 1 and Angle 2
R3. Congruent (___)
R5. supplementary angles
S7. Angle 1 = Angle 2, so Angle 1 can be substitued in for Angle 2 in any equation, and Angle 2 can be substitued for Angle 1 in any equation as well (they can replace each other, like x=y & y=x or a=b & b=a)
Hope this helped! Have a great day (pls mark brainliest)!!
