The first one is a proportional relationship.
Answer: x=75
Explanation:
x+10+x+20=180
combine like terms
2x+30=180
subtract 30 from each side
2x=150
divide each side by 2
x=75
36/9. I hope this helped. :) Brainlest answer please?
A proportional relationship is just a linear relationship where b = 0, or to put it another way, where the line passes through the origin (0,0).