Answer:
z = 12
Step-by-step explanation:
The two marked inscribed angles intercept the same arc, so have the same measure.
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∠ADB = ∠ACB
7z -4 = 5z +20 . . . . . . substitute degree measures
2z = 24 . . . . . . . . add 4-5z
z = 12 . . . . . . . divide by 2
