Answer: 
Step-by-step explanation:
Using the same-side interior angles theorem,
.
Using the alternate interior angles theorem, 
Answer:
how
Step-by-step explanation:
3 (2x + 1) = 21
6x + 3= 21
-3 -3
6x = 18
Divide each side by 6, and x equals 3.
3 (2(3) + 1) = 21
3 (6 + 1) = 21
18 + 3 = 21
Hope this helps! Can I please have brainliest so I can level up? Thank you!
Then? You didn't type the full question
Idk this is hard sorry I couldn't help you but you just helped me