document.write( "Question 189311: How many liters of a 30% alcohol solution and how many of a 60% alcohol solution must be mixed to produce 18 liters of a 50% alcohol solution? \n" ); document.write( "
Algebra.Com's Answer #142023 by nerdybill(7384)\"\" \"About 
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How many liters of a 30% alcohol solution and how many of a 60% alcohol solution must be mixed to produce 18 liters of a 50% alcohol solution?
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\n" ); document.write( "Let x = liters of 30% alcohol
\n" ); document.write( "and y = liters of 60% alcohol
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\n" ); document.write( "Then, since we have two unknowns we need two equations:
\n" ); document.write( "x + y = 18 (equation 1)
\n" ); document.write( ".30x + .60y = .50(x+y) (equation 2)
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\n" ); document.write( "Solve equation 1 for y:
\n" ); document.write( "x + y = 18
\n" ); document.write( "y = 18-x
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\n" ); document.write( "Substitute the above into equation 2 and solve for x:
\n" ); document.write( ".30x + .60y = .50(x+y)
\n" ); document.write( ".30x + .60(18-x) = .50(x+18-x)
\n" ); document.write( ".30x + 10.8 - .60x = .50(18)
\n" ); document.write( "10.8 - .30x = 9
\n" ); document.write( "-.30x = -1.8
\n" ); document.write( "x = 6 liters (of 30% alcohol)
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\n" ); document.write( "Substitute the above into equation 1 and solve for y:
\n" ); document.write( "x + y = 18
\n" ); document.write( "6 + y = 18
\n" ); document.write( "y = 12 liters (of 60% alcohol)\r
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