Answer: x = 10
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Step-by-step explanation:
The square marker in the top left corner tells us we have a 90 degree angle. The 8x+10 must also be 90 degrees for lines u and v to be parallel. Refer to the alternate exterior angle theorem. Ignore the diagonal lines. Your teacher likely put them there as a distraction.
8x+10 = 90
8x = 90-10
8x = 80
x = 80/8
x = 10