Which equation can be used to solve for x in the following diagram?

Answer:
d
Step-by-step explanation:
to find the answer you have to set everything equal to 180
then simplify
then you get x
Answer:
A
Step-by-step explanation:
As the sum of angles should be 0 for a straight line, 3x+8x-20+90=180, 3x+8x-20=90