Sorry this took a while but it should be the last option for it to be correct.
Answer: 
<u>Move all terms to the left</u>
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<u>Add all the numbers together, and all the variables</u>
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<u>Multiply elements</u>
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<u>Move all terms containing d to the left, all other terms to the right</u>
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Answer:
D
Step-by-step explanation:
You can look at it like a right triangle being made with the vertical part being 9 and the horizontal part being 8, then you want to find the diagonal part. So that's the Pythagorean theorem

Answer:
Yes
Step-by-step explanation:
90 degrees in a right angle.