document.write( "Question 522918: If one blend of coffee sells for $9.00 per pound and another blend sells for $8.00 per pound how many of each type should be used to maake a 20 pond blend that sells for $8.40 per pound? \n" ); document.write( "

Algebra.Com's Answer #347078 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"a\"$ = pounds of $9 coffee needed
\n" ); document.write( "Let $\"b\"$ = pounds of $8 coffee needed
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+a+%2B+b+=+20+\"$
\n" ); document.write( "(2) $\"+%289a+%2B+8b%29+%2F+20+=+8.4+\"$
\n" ); document.write( "----------------------
\n" ); document.write( "(2) $\"+%289a+%2B+8b%29+%2F+20+=+8.4+\"$
\n" ); document.write( "(2) $\"+9a+%2B+8b+=+20%2A8.4+\"$
\n" ); document.write( "(2) $\"+9a+%2B+8b+=+168+\"$
\n" ); document.write( "Multiply both sides of (1) by $\"8\"$ and
\n" ); document.write( "subtract (1) from (2)
\n" ); document.write( "(2) $\"+9a+%2B+8b+=+168+\"$
\n" ); document.write( "(1) $\"+-8a+-+8b+=+160+\"$
\n" ); document.write( " $\"+a+=+8+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"+a+%2B+b+=+20+\"$
\n" ); document.write( "(1) $\"+8+%2B+b+=+20+\"$
\n" ); document.write( "(1) $\"+b+=+12+\"$
\n" ); document.write( "8 pounds of $9 coffee are needed
\n" ); document.write( "12 pounds of $8 coffee are needed
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+%289a+%2B+8b%29+%2F+20+=+8.4+\"$
\n" ); document.write( "(2) $\"+%289%2A8+%2B+8%2A12%29+%2F+20+=+8.4+\"$
\n" ); document.write( "(2) $\"+%2872+%2B+96%29+=+8.4%2A20+\"$
\n" ); document.write( "(2) $\"+168+=+168+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );