It would be 15 because the way you would set it up is equal to 180 because they are opposite and they have to add up to 180 in order for the whole shape to be 360. so 3x+9x=180 and then 12x=180 and divide 180 by 12 which is 15 and you can also plug in 15 to check
Answer:
Is this the whole question or u cut it?
Answer:
Isolate the variable by dividing each side by factors that don't contain the variable.

Answer:
B
Step-by-step explanation:
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