Answer: x=55
Explanation:
Since the lines are parallel, the two angles on the line are supplementary angles.
It means they would add to 180.
1) Set up the equation
(2x+6)+(x+9)=180
2) Combine like terms
3x+15 = 180
3) Move the 15 to the other side to leave x
3x = 180 - 15
3x = 165
4) Set x by itself
x = 165/3
x=55