Using the following diagram, which is the value of x ?

Answer:
B. x = 20
Step-by-step explanation:
angles on a straight line are supplementary
therefore, 6x+9 + 2x+11 = 180
so, 8x+20=180
8x = 160
x = 20
Answer:
B
Step-by-step explanation:
If you substitute the x values with 20 then the angles will add up to 180 on both sides. These angles are supplementary which means that they are suppose to add up to 180 degrees.