SOLUTION: A mechanic has 340 gallons of gasoline and 10 gallons of oil to make gas/oil mixtures. He wants one mixture to be 4% oil and the other mixture to be 2.5% oil. If he wants to use al

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Question 488190: A mechanic has 340 gallons of gasoline and 10 gallons of oil to make gas/oil mixtures. He wants one mixture to be 4% oil and the other mixture to be 2.5% oil. If he wants to use all of the gas and oil, how many gallons of gas and oil are in each of the resulting mixtures?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = total gallons of gas + oil in the 4% oil mixture
Let +b+ = total gallons of gas + oil in the 2.5% oil mixture
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given:
The % of gas in the 4% oil mixture is 96%
The % of gas in the 2.5% oil mixture is 97.5%
+340+%2B+10+=+350+ total gallons of gas + oil in the 2 mixtures
(1) +a+%2B+b+=+350+
(2) +.96a+%2B+.975b+=+340+
(3) +.04a+%2B+.025b+=+10+
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Multiply both sides of (2) and (3) by +1000+
(1) +a+%2B+b+=+350+
(2) +960a+%2B+975b+=+340000+
(3) +40a+%2B+25b+=+10000+
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Multiply both sides of (3) by +39+
and subtract (2) from (3)
(3) +1560a+%2B+975b+=+390000+
(2) +-960a+-+975b+=+-340000+
+600a+=+50000+
+a+=+83.333+
and, since
(1) +a+%2B+b+=+350+
(1) +b+=+350+-+83.333+
(1) +b+=+266.667+
-----------------
+.96a+=+.96%2A83.333+
+.96a+=+80+ gallons
+83.333+-+80+=+3.333+ gallons
and
+.975b+=+.975%2A266.667+
+.975b+=+260+ gallons
+266.667+-+260+=+6.6667+
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There are 80 gallons of gas in the 4% oil mixture
There are 3 and 1/3 gallons of oil in the 4% oil mixture
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There are 260 gallons of gas in the 2.5% oil mixture
There are 6 and 2/3 gallons of oil in the 2.5% oil mixture
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check:
+80+%2B+3+%2B+1%2F3+%2B+260+%2B+6+%2B+2%2F3+=+350+
+349+%2B+3%2F3+=+350+
+350+=+350+
OK
and +80+%2B+260+=+340+
and +3+%2B+1%2F3+%2B+6+%2B+2%2F3+=+10+
OK