document.write( "Question 991979: Sam needs 3 lb of metal with 43% silver. If sam combines one metal with 18% silver, and another with 80% silvet, how much metal does he need? \n" ); document.write( "
Algebra.Com's Answer #611653 by josmiceli(19441)\"\" \"About 
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Let \"+a+\" = pounds of 18% silver needed
\n" ); document.write( "Let \"+b+\" = pounds of 80% silver needed
\n" ); document.write( "-----------------
\n" ); document.write( "(1) \"+a+%2B+b+=+3+\"
\n" ); document.write( "(2) \"+%28+.18a+%2B+.8b+%29+%2F+3+=+.43+\"
\n" ); document.write( "---------------------------
\n" ); document.write( "(2) \"+.18a+%2B+.8b+=+1.29+\"
\n" ); document.write( "(2) \"+18a+%2B+80b+=+129+\"
\n" ); document.write( "Multiply both sides of (1) by \"+18+\"
\n" ); document.write( "and subtract (1) from (2)
\n" ); document.write( "(2) \"+18a+%2B+80b+=+129+\"
\n" ); document.write( "(1) \"+-18a+-+18b+=+-54+\"
\n" ); document.write( "----------------------
\n" ); document.write( "\"+62b+=+75+\"
\n" ); document.write( "\"+b+=+1.21\"
\n" ); document.write( "and
\n" ); document.write( "(1) \"+a+%2B+b+=+3+\"
\n" ); document.write( "(1) \"+a+=+1.79+\"
\n" ); document.write( "1.79 pounds of 18% silver are needed
\n" ); document.write( "1.21 pounds of 80% silver are needed
\n" ); document.write( "-------------------------------
\n" ); document.write( "check:
\n" ); document.write( "(2) \"+%28+.18%2A1.79+%2B+.8%2A1.21+%29+%2F+3+=+.43+\"
\n" ); document.write( "(2) \"+%28+.3222+%2B+.968+%29+%2F+3+=+.43+\"
\n" ); document.write( "(2) \"+1.29+=+3%2A.43+\"
\n" ); document.write( "(2) \"+1.29+=+1.29+\"
\n" ); document.write( "OK
\n" ); document.write( "
\n" );