SOLUTION: A computer online service charges one hourly price for regular use, but a higher hourly rate for designed "premium" areas. One customer was charged $28 after spending two hours in
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Question 177558: A computer online service charges one hourly price for regular use, but a higher hourly rate for designed "premium" areas. One customer was charged $28 after spending two hours in premium areas and nine regular hours. Another spent three hours in premium areas and six regular hours and was charged $27. What does the online service charge per hour for regular and premium services? Answer by Mathtut(3670) (Show Source):
You can put this solution on YOUR website! let r and p be the charge per hour of regular and premium services, respectively
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9r+2p=28......eq 1
6r+3p=27......eq 2
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multiply eq 1 by -3 and eq 2 by 2 and add the equations together
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-27r-6p=-84...revised eq 1
12r+6p=54.....revised eq 2
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you can see that the p terms are eliminated because -6p+6p=0. We are left with
-27r+12r=-84+54
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-15r=-30
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$per hour for regular
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now take r's found value and plug it into either eq 1 or 2. I chose eq 2
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9(2)+2p=28
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2p=10
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$per hour for premium
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