document.write( "Question 178565: what quantity x of an 80% solution must be added to a 15% solution to produce 600mL of a 40% solution \n" ); document.write( "

Algebra.Com's Answer #133524 by jojo14344(1513) $\"\"$ $\"About$

You can put this solution on YOUR website!

\n" ); document.write( "We know $\"x\"$ =ml of 80%
\n" ); document.write( "Let $\"y\"$ =ml of 15%
\n" ); document.write( "Then, $\"x%2By=600ml\"$ ---------------------> EQN 1
\n" ); document.write( "Also, when mixed:
\n" ); document.write( " $\"0.80%28x%29%2B0.15%28y%29=600%280.40%29\"$ -----------> EQN 2
\n" ); document.write( "Goin back EQN 1 we get,
\n" ); document.write( " $\"x=600-y\"$ ----------------------------> EQN 3, subst. in EQN 2:
\n" ); document.write( " $\"0.80%28600-y%29%2B0.15y=240\"$
\n" ); document.write( " $\"480-0.80y%2B0.15y=240\"$
\n" ); document.write( " $\"480-240=0.80y-0.15y\"$
\n" ); document.write( " $\"240=0.65y\"$ ----------> $\"cross%28240%29369.23%2Fcross%280.65%29=cross%280.65%29y%2Fcross%280.65%29\"$
\n" ); document.write( " $\"y=369.23ml\"$ needed for 15% sol'n.
\n" ); document.write( "Going back EQN 3:
\n" ); document.write( " $\"x=600-369.23=highlight%28230.77ml%29\"$ , needed for the 80% sol'n.
\n" ); document.write( "In doubt? Go back EQN 2:
\n" ); document.write( " $\"0.80%28230.77%29%2B0.15%28369.23%29=600%280.40%29\"$
\n" ); document.write( " $\"184.616%2B55.3845=240ml\"$
\n" ); document.write( " $\"240ml=240ml\"$
\n" ); document.write( "Thank you,
\n" ); document.write( "Jojo
\n" ); document.write( " \n" ); document.write( "

\n" );