document.write( "Question 943931: Tom has a $20 bill, a $10 bill, a $5 bill, and $1 bill. List the total costs possible for items he could buy if he receives no change. \n" ); document.write( "
Algebra.Com's Answer #575578 by KMST(5328)\"\" \"About 
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The cost, in $, of an item that could be purchased receiving no change is
\n" ); document.write( "\"20a%2B10b%2B5c%2B1d\" where
\n" ); document.write( "\"a\" , \"b\" , \"c\" , and \"d\" are \"0\" or \"1\" .
\n" ); document.write( "That means 2 choices for each variable, and
\n" ); document.write( "\"2%2A2%2A2%2A2=2%5E4=16\" choices overall.
\n" ); document.write( "One of those \"16\" choices is \"0\" .
\n" ); document.write( "I suppose $0 would mean not buying anything,
\n" ); document.write( "so if some amount was paid,
\n" ); document.write( "it has to be one of the remaining \"16-1=highlight%2815%29\" possible amounts.
\n" ); document.write( "
\n" ); document.write( "Now that I know there are 15, I list the amounts,
\n" ); document.write( "and count them to make sure I do not forget any:
\n" ); document.write( "With a $1 bill (\"a=1\" ):
\n" ); document.write( "$1,
\n" ); document.write( "and if we also add a $5 bill (\"system%28a=1%2Cb=1%29\" ),
\n" ); document.write( "$1+$5=$6
\n" ); document.write( "$1+$5+$10=$16
\n" ); document.write( "$1+$5+$10+$20=$36
\n" ); document.write( "$1+$5+$20=$26
\n" ); document.write( "With a $1 bill, and a $10 bill, but no $5 bill (\"system%28a=1%2Cb=0%2Cc=1%29%29\" ),
\n" ); document.write( "$1+$10=$11
\n" ); document.write( "$1+$10+$20=$31
\n" ); document.write( "With a $1 bill, and another bill, but no $5 or $10 bill,
\n" ); document.write( "$1+$20=$21
\n" ); document.write( "With no $1 bill \"a=0\" ), but including one $5 bill ( \"b=1\" ):
\n" ); document.write( "$5
\n" ); document.write( "$5+$10=$15
\n" ); document.write( "$5+$10+$20=$35
\n" ); document.write( "$5+$20=$25
\n" ); document.write( "If no $1 or $5 bill is used ( \"a=b=0\" ):
\n" ); document.write( "$10
\n" ); document.write( "$10+$20=$30
\n" ); document.write( "$20
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