Answer:
Let x = quarts of water to be added
so then
12* 10% + x * 0% = (12+x) * 6% (this says 12 quarts of 10% solution + x quarts of 0%(water) equals the new total (12+x) of a 6% solution
1.2 = .72 + .06x
.48 = .06x
x = 8 (quarts of water to be added)
Explanation:
Hope this helps