Answer:
[tex](3x+14)+(8x-21)=180°[/tex]
Step-by-step explanation:
Angles with measures [tex]3x+14[/tex] and [tex]8x-21[/tex] (or pmore precisely, vertical angle to angle 8x-21) are supplementary (add up to 180°).
Converse to same-side interior angles theorem states that If two same-side interior angles are supplementary, then l║p.
So, to prove that lines l and p are parallel, you have to show that angles [tex]3x+14[/tex] and [tex]8x-21[/tex] are supplementary.
Thus,
[tex](3x+14)+(8x-21)=180°[/tex]
