document.write( "Question 159015: Warren has 40 coins; nickels dimes and quarters worth $4.05. He has seven more nickels than dimes. How many quarters does he have? \n" ); document.write( "
Algebra.Com's Answer #117182 by ankor@dixie-net.com(22740)\"\" \"About 
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Warren has 40 coins; nickels dimes and quarters worth $4.05. He has seven more nickels than dimes. How many quarters does he have?
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\n" ); document.write( "Write 3 equations, one for each statement:
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\n" ); document.write( "\"Warren has 40 coins;\"
\n" ); document.write( "n + d + q = 40; eq1
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\n" ); document.write( "\" nickels dimes and quarters worth $4.05.\"
\n" ); document.write( ".05n + .10d + .25q = 4.05; eq2
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\n" ); document.write( "\"He has seven more nickels than dimes.\"
\n" ); document.write( "n = d + 7
\n" ); document.write( "n - d = 7; eq3
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\n" ); document.write( "Add equations 1 and 3:
\n" ); document.write( "n + d + q = 40
\n" ); document.write( "n - d + 0 = 7
\n" ); document.write( "------------------adding eliminates d
\n" ); document.write( "2n + q = 47
\n" ); document.write( "q = (47-2n)
\n" ); document.write( ":
\n" ); document.write( "Multiply eq2 by 10, subtract eq1
\n" ); document.write( ".5n + 1d + 2.5q = 40.5
\n" ); document.write( "1n + 1d + 1q = 40
\n" ); document.write( "------------------------subtraction eliminates d again
\n" ); document.write( "-.5n + 0 + 1.5q = .5
\n" ); document.write( "-.5n + 1.5q = .5
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\n" ); document.write( "Substitute (47-2n) for q in the above equation, find n
\n" ); document.write( "-.5n + 1.5(47-2n) = .5
\n" ); document.write( "-.5n + 70.5 - 3n = .5
\n" ); document.write( "-.5n - .3n = .5 - 70.5
\n" ); document.write( "-3.5n = -70
\n" ); document.write( "n = \"%28-70%29%2F%28-3.5%29\"
\n" ); document.write( "n = +20 nickels
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\n" ); document.write( "Find d;
\n" ); document.write( "n - d = 7
\n" ); document.write( "20 - d = 7
\n" ); document.write( "d = 13 dimes
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\n" ); document.write( "Obviously, that leaves us with 7 quarters.
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\n" ); document.write( "You should check these solutions using eq2:
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