Question 380613
  <pre><font size = 3 color = "indigo"><b>
Hi,
Let x represent the amount of the 100% pure acid solution
1.00x + .40*2gal = .80*(x + 2gal)
solving for x
.20x = .40*2gal
x = 4 gal of pure acid needed.

CHECKING our Answer
4 + .8 = 4.8 = .8*6