Answer:
x = 90, y = 12
Step-by-step explanation:
The key to this problem is the fact that opposite sides of a parallelogram are congruent (their lengths are equal).
Set up and solve two equations, one for x and one for y.
x + 80 = 2x - 10
80 = x - 10
90 = x
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3y - 4 = y + 20
2y - 4 = 20
2y = 24
y = 12
