document.write( "Question 331642: What quantity of 60 per cent acid solution must be mixed with a 20 percent solution to produce 720 mL of a 50 per cent solution? \n" ); document.write( "

Algebra.Com's Answer #237741 by jrfrunner(365) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let X = amount of 60% solution needed
\n" ); document.write( "Let Y = amount of 20% solution needed
\n" ); document.write( "==
\n" ); document.write( "You are given information to form two equations and you have two unknowns
\n" ); document.write( "which are necessary conditions to solve the problem\r
\n" ); document.write( "\n" ); document.write( "equation 1 (amounts): X+Y =720ml
\n" ); document.write( "equation 2 (concentrations): 0.6*X+0.2*Y=0.5(720)
\n" ); document.write( "===\r
\n" ); document.write( "\n" ); document.write( "solve equation 1 for one of the variables (ie Y): Y=720-X
\n" ); document.write( "multiply equation 2 by 10 to make into whole numbers
\n" ); document.write( "6*X+2Y=5*720
\n" ); document.write( "substitute Y=720-X into previous equation
\n" ); document.write( "6*x+2*(720-X)=3600
\n" ); document.write( "6x+1440-2x=3600
\n" ); document.write( "4x=3600-1440=2160
\n" ); document.write( "x=540
\n" ); document.write( "===
\n" ); document.write( "y=720-x
\n" ); document.write( "y=720-540=180\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

\n" );