Answer: 80
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Explanation:
For any inscribed quadrilateral like this, the opposite angles are always supplementary. This means the angles add to 180
B+D = 180
(2x-1) + (3x-59) = 180
(2x+3x) + (-1-59) = 180
5x-60 = 180
5x = 180+60
5x = 240
x = 240/5
x = 48
Use this x value to find angle A
A = 2x+4
A = 2*48+4
A = 96+4
A = 100
This then means,
A+C = 180
C = 180-A
C = 180-100
C = 80 degrees
Side note: The term "cyclic quadrilateral" is the same as "inscribed quadrilateral".
