Answer:
A = 125º
Step-by-step explanation:
Missing angle is the supplement of 157.5
180 - 157.5 = 22.5
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Sum of angles in triangle is 180
22.5 + (-10x) + (-x + 20) = 180
Combine like terms
-11x + 42.5 = 180
Subtract 42.5 from both sides
-11x = 137.5
Divide both sides by -11
x = -12.5
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A = -10(-12.5)
A = 125º
