<PRE><B>Question 958839</B>
A gas station sells three types of gas: Regular for $2.90 a gallon, Performance Plus for $3.05 a gallon, and Premium for $3.20 a gallon. 
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On a particular day 5000 gallons of gas were sold for a total of $14,920. Three times as many gallons of Regular as Premium gas were sold. How many gallons of each type of gas were sold that day?
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r + pp + p = 5000 gallons
2.9r + 3.05pp + 3.20p = 14920
r = 3p
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Substitute::
4p + pp = 5000
11.9p + 3.05pp = 14920
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Modify::
12.2p + 3.05pp = 15250
11.9p + 3.05pp = 14920
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Subtract:
0.3p = 330
p = 1100 (# of gallons of Premium sold)
r = 3p = 3300 (# of gallons of regular sold)
pp = 5000 - 4400 = 600 (# of gallons of Premium Plus sold)
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Cheers,
Stan H.
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