document.write( "Question 708706: a scientist wants to make a solution that is 30% acid using one solution that is 50 % acid and another solution that is 20% acid.How many liters of each solution does the scientist need to make 75 liters of the mixture? \n" ); document.write( "
Algebra.Com's Answer #436219 by josgarithmetic(39617)\"\" \"About 
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\"v\"= known resulting volume, 75 liters
\n" ); document.write( "\"p%5B1%5D\" = low concentration material, 20%
\n" ); document.write( "\"p%5B2%5D\" = high concentration material, 50%
\n" ); document.write( "\"p%5Bt%5D\" = the target concentration of mixture, 30%
\n" ); document.write( "\"x\" = how much low concentration material to use
\n" ); document.write( "\"y\" = how much high concentration material to use\r
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\n" ); document.write( "\n" ); document.write( "INITIAL SYSTEM
\n" ); document.write( "\"%28xp%5B1%5D%2Byp%5B2%5D%29%2Fv=p%5Bt%5D\"
\n" ); document.write( "\"x%2By=v\"\r
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\n" ); document.write( "\n" ); document.write( "Work with and possibly do other simplifications to the percent-concentration equation,
\n" ); document.write( "\"%28xp%5B1%5D%2Byp%5B2%5D%29=vp%5Bt%5D\"\r
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\n" ); document.write( "\n" ); document.write( "Use the volume sum equation to solve for either variable and substitute into the percentage equation and find the single variable there. As general example, solve for y:\r
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\n" ); document.write( "\n" ); document.write( "x+y=v, \"y=v-x\". Substitute.
\n" ); document.write( "\"%28xp%5B1%5D%2B%28v-x%29p%5B2%5D%29=vp%5Bt%5D\", and solve for x
\n" ); document.write( "\"xp%5B1%5D%2Bvp%5B2%5D-xp%5B2%5D=vp%5Bt%5D\"
\n" ); document.write( "\"xp%5B1%5D-xp%5B2%5D=-vp%5B2%5D%2Bvp%5Bt%5D\"
\n" ); document.write( "\"x%28p%5B1%5D-p%5B2%5D%29=-vp%5B2%5D%2Bvp%5Bt%5D\"
\n" ); document.write( "\"x%28p%5B2%5D-p%5B1%5D%29=vp%5B2%5D-vp%5Bt%5D\" Equivalent to multiplying both sides by -1
\n" ); document.write( "\"x=v%28v%5B2%5D-p%5Bt%5D%29%2F%28p%5B2%5D-p%5B1%5D%29\"
\n" ); document.write( "And that would be the symbolic form for x, the lower concentration material. Just substitute the given values.
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