Question

Find angle x

i have worked out the answer and put my reasoning but isnt giving me full marks please could someone explain
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Answer 1

`x=80^(\circ)`

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.

Answer 2

x = 80 degree

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