Answer:
3 gallons
Step-by-step explanation:
Let
x ----> the amount of pure acid (100% solution) in gallons
Remember that
[tex]100\%=100/100=1[/tex]
[tex]20\%=20/100=0.20[/tex]
[tex]60\%=60/100=0.60[/tex]
we know that
[tex](1)(x)+(0.20)(3)=(0.60)(x+3)[/tex]
solve for x
[tex]x+0.60=0.60x+1.80[/tex]
[tex]x-0.60x=1.80-0.60\\0.40x=1.20\\x=3\ gal[/tex]
therefore
3 gallons of pure acid should be mixed with 3 gallons of a 20% acid solution in order to get a 60% acid solution
