document.write( "Question 136924: When Frank Gresham drove 150 miles in the city, the fuel efficency rating for his car was 18mi/gal. For Highway driving, the fuel efficiency rating is 24 mi/gal. How far will Frank have to drive on the highway for his car to have a fuel efficency rating of 20mi/gal \n" ); document.write( "
Algebra.Com's Answer #100226 by ankor@dixie-net.com(22740)\"\" \"About 
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When Frank Gresham drove 150 miles in the city, the fuel efficiency rating for his car was 18mi/gal. For Highway driving, the fuel efficiency rating is 24 mi/gal. How far will Frank have to drive on the highway for his car to have a fuel efficiency rating of 20mi/gal
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\n" ); document.write( "Treat it like a mixture problem
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\n" ); document.write( "Let x = no, miles required to get an efficiency rating of 20 mi/gal
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\n" ); document.write( "18(150) + 24x = 20(x+150)
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\n" ); document.write( "2700 + 24x = 20x + 3000
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\n" ); document.write( "24x - 20x = 3000 - 2700
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\n" ); document.write( "3x = 300
\n" ); document.write( "x = \"300%2F3\"
\n" ); document.write( "x = 100 miles
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\n" ); document.write( "Let's see if that works
\n" ); document.write( "At 18 mpg: 150/18 = 8.33 gal
\n" ); document.write( "At 24 mpg: 100/24 = 4.17 gal
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\n" ); document.write( "the total gallons = 12.5
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\n" ); document.write( "Av for trip: 250/12.5 = 20 mpg; confirms our solution \n" ); document.write( "
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