document.write( "Question 435249: You are making 10 tons of concrete that is
\n" ); document.write( "36.2% cement by mixing a 17% cement mix-
\n" ); document.write( "ture with a 65% cement mixture.
\n" ); document.write( "a) How much of the 65% cement mixture
\n" ); document.write( "must you use?
\n" ); document.write( "Answer in units of tons. \n" ); document.write( "

Algebra.Com's Answer #301286 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"a\"$ = tons of 17% mixture needed
\n" ); document.write( "Let $\"b\"$ = tons of 65% mixture needed
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+a+%2B+b+=+10+\"$ tons
\n" ); document.write( "(2) $\"+.17a+%2B+.65b+=+.362%2A10+\"$
\n" ); document.write( "------------------------
\n" ); document.write( "(2) $\"+.17a+%2B+.65b+=+3.62+\"$
\n" ); document.write( "(2) $\"+17a+%2B+65b+=+362+\"$
\n" ); document.write( "Multiply both sides of (1) by $\"17\"$
\n" ); document.write( "and subtract (1) from (2)
\n" ); document.write( "------------------------
\n" ); document.write( "(2) $\"+17a+%2B+65b+=+362+\"$
\n" ); document.write( "(1) $\"+-17a+-+17b+=+170+\"$
\n" ); document.write( " $\"+48b+=+192+\"$
\n" ); document.write( " $\"+b+=+4+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"+a+%2B+b+=+10+\"$
\n" ); document.write( " $\"+a+=+6+\"$
\n" ); document.write( "6 tons of 17% mixture are needed
\n" ); document.write( "4 tons of 65% mixture are needed
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+.17a+%2B+.65b+=+3.62+\"$
\n" ); document.write( "(2) $\"+.17%2A6+%2B+.65%2A4+=+3.62+\"$
\n" ); document.write( " $\"+1.02+%2B+2.6+=+3.62+\"$
\n" ); document.write( " $\"+3.62+=+3.62+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );