Question 186561
a movie theater charges $8.00 for adults, $4.50 for children, and $6.00 for senior citizens. one day the theatre sold 405 tickets and collected $2320 in receipts. there were twice as many children's tickets sold as adult tickets. how many adults, children, and senior citizens went to the theater that day?
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Quantity equation: 
a + c + s = 405
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Value equation:
8a + 4.5c + 6s = 2320
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Quantity equation:
c = 2a
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Rearrange the equations:
a   +   c   +   s   = 405
8a  +  4.5c +  6s   = 2320
2a  -   c   +   0   = 0
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Solve the system by any means you know to get:
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a = 110
c = 220
s = 75
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Cheers,
Stan H.