20 ! can someone explain this to me, as well as me with the question?

D.

Step-by-step explanation:

It's impossible to know if either A or B is true based on the information given to us in the diagram, so it cannot be A or B. C is false because all three of the angles in a triangle add up to 180°, and the equation in C only includes two angles. So the answer is D because it is the only statement we know to absolutely be true. Both angles three and four share one line (a line is 180°), so their sum must be 180°.

here is your mark brainliest

answer:

a=9

step-by-step explanation: lmk if you need a explanation