document.write( "Question 181451: Lorena bought 10 packs of styrofoam cups for the graduation dance. a pack of fifty 12-oz cups costs $1.80 and apack of fifty 16-oz cups costs $2.40. Lorena paid a total of $21.60 excluding tax. How many packs of each size cup did she buy? \n" ); document.write( "

Algebra.Com's Answer #136060 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"a\"$ = the number of packs of 12 oz cups she bought
\n" ); document.write( "Let $\"b\"$ = the number of packs of 16 oz cups she bought
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"a+%2B+b+=+10\"$
\n" ); document.write( "(2) $\"180a+%2B+240b+=+2160\"$
\n" ); document.write( "Multiply both sides of (1) by 180 and subtract from (2)
\n" ); document.write( "(2) $\"180a+%2B+240b+=+2160\"$
\n" ); document.write( "(1) $\"-180a+-+180b+=+-1800\"$
\n" ); document.write( " $\"60b+=+360\"$
\n" ); document.write( " $\"b+=+6\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"a+%2B+b+=+10\"$
\n" ); document.write( " $\"a+%2B+6+=+10\"$
\n" ); document.write( " $\"a+=+4\"$
\n" ); document.write( "She bought 4 packs of 12 oz cups and
\n" ); document.write( "6 packs of 16 oz cups
\n" ); document.write( "check answer:
\n" ); document.write( "(2) $\"180a+%2B+240b+=+2160\"$
\n" ); document.write( "(2) $\"180%2A4+%2B+240%2A6+=+2160\"$
\n" ); document.write( " $\"720+%2B+1440+=+2160\"$
\n" ); document.write( " $\"2160+=+2160\"$
\n" ); document.write( "OK \n" ); document.write( "

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