Answer: 6 orchestra tickets were purchased
Explanation:
orchestra purchased tickets = x
balcony purchased tickets = y
ou purchase nine tickets
total cost of $720
x + y = 9
90x + 60y = 720
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x + y = 9 (*-60)
90x + 60y = 720
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-60x - 60y = -540
90x + 60y = 720 (+)
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30x = 180
x = 6