Question

Find angle x

Answer 1

Answer:

x = 80 degree

Step-by-step explanation:

angle B = 100 degree (being vertically opposite angle)

angle B + angle x = 180 degree ( being same side interior angles or also said as co interior angles )

100 + x = 180

x = 180 - 100

x = 80 degree

Answer 2

Answer:

$x=80^{\circ}$

Step-by-step explanation:

The answer is correct and the reasoning is fine. I'd mention that that $\angle x$ corresponds with angle $\angle ABC$ and since $\angle ABC$ and $\angle CBD$ form one side of a line, they are supplementary (add up to 180 degrees). Therefore, $x=180^{\circ}-100^{\circ}=\boxed{80^{\circ}}$.Your reasoning is correct as well, but maybe just add on and explain that $m\angle B=m\angle CBD$ because they are vertical angles.

In addition, I have a hard time believing a computer will be able to grade the reasoning portion of the question well. It's entirely possible it isn't giving you credit for that because it needs to be manually graded.