document.write( "Question 630481: How many gallons of a 12%-salt solution must be mixed with 6 gallons of a 21%-salt solution to obtain a 15%-salt solution? \n" ); document.write( "
Algebra.Com's Answer #396931 by Maths68(1474)\"\" \"About 
You can put this solution on YOUR website!
Solution A
\n" ); document.write( "Amount = x gallons
\n" ); document.write( "Concentration =12% =0.12\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Solution B
\n" ); document.write( "Amount = 6 gallons
\n" ); document.write( "Concentration =21% = 0.21\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Resultant Solution
\n" ); document.write( "Amount =6+x gallons
\n" ); document.write( "Concentration =15%=0.15\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "[Amount Solution A * Concentration A] + [Amount Solution B * Concentration of B] = Amount of Resultant * Concentration of resultant\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "(x)(0.12) + (6)(0.21) = (6+x)(0.15)
\n" ); document.write( "0.12x+1.26=0.9+0.15x
\n" ); document.write( "0.12x-0.15x=0.9-1.26
\n" ); document.write( "-0.03x=-0.36
\n" ); document.write( "-0.03x/-0.03=-0.36/0.03
\n" ); document.write( "x=12\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "12 gallons of a 12%-salt solution must be mixed with 6 gallons of a 21%-salt solution to obtain 18 gallons of a 15%-salt solution?
\n" ); document.write( " \n" ); document.write( "
\n" );