document.write( "Question 1013111: An ice cream parlor made $200. They sold cups for $0.60, and cones for $2. How much cups of ice cream did they sell, and how many cones of ice cream did they sell?\r
\n" ); document.write( "\n" ); document.write( "I tried dividing $200 by $0.60, but what about the cones? \r
\n" ); document.write( "\n" ); document.write( "PLEASE EXPLAIN STEPS
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Algebra.Com's Answer #629289 by KMST(5328)\"\" \"About 
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\"x\"= number of cups sold
\n" ); document.write( "\"y\"= number of cones sold
\n" ); document.write( "\"0.6x\"= money (in $) made by selling \"x\" cups
\n" ); document.write( "\"2y\"= money (in $) made by selling \"y\" cones
\n" ); document.write( "\"0.6x%2B2y=200\"= total money (in $) made by selling \"x\" cups and \"y\" cones.
\n" ); document.write( "I would expect another piece of information, such as the fact that they served a certain number of customers.
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\n" ); document.write( "IF the problem stated that \"135\" servings (between cones and cups) were sold
\n" ); document.write( "we would write that \"x%2By=135\" , and we would find \"x\" and \"y\" .
\n" ); document.write( "by solving the system of linear equations \"system%28x%2By=135%2C0.6x%2B2y=200%29\"
\n" ); document.write( "\"system%28x%2By=135%2C0.6x%2B2y=200%29\"--->\"system%28y=135-x%2C0.6x%2B2y=200%29\"--->\"system%28y=135-x%2C0.6x%2B2%28135-x%29=200%29\"--->\"system%28y=135-x%2C0.6x%2B270-2x=200%29\"--->\"system%28y=135-x%2C0.6x-2x=200-270%29\"
\n" ); document.write( "--->\"system%28y=135-x%2C-1.4x=-70%29\"--->\"system%28y=135-x%2Cx=%28-70%29%2F%28-1.4%29%29\"--->\"system%28y=135-x%2Cx=50%29\"--->\"system%28y=135-50%2Cx=50%29\"--->\"system%28y=85%2Cx=50%29\"
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\n" ); document.write( "Since \"0.6x%2B2y=200\" is the only equation you can write from the information given,
\n" ); document.write( "we should expect to find more than one solution.
\n" ); document.write( "Only fact that \"x\" and \"y\" must both be integers keeps the problem from having \"infinity\" solutions.
\n" ); document.write( "\"0.6x%2B2y=200\"<-->\"0.3x%2By=100\"<-->\"y=100-0.3x\"
\n" ); document.write( "For \"y\" to be an integer, we need \"0.3x\"} to be an integer,
\n" ); document.write( "and for \"0.3x=3x%2F10\" to be an integer, \"x\" must be a multiple of \"10\" .
\n" ); document.write( "So we take non-negative values for \"x\" that can be divided by \"10\" ,
\n" ); document.write( "calculate \"y=100-0.3x\" for each \"x\" value,
\n" ); document.write( "and tabulate all the many solutions we find:
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