How much pure water must be mixed with 3 pints of 60% developer to produce a mixture that is 23% developer?
Note that pure water = 0% developer
So.....call the amount of pure water, W and we have that
0% (W) + .60 (3) = .23 ( W + 3) simplify
1.8 = .23W + .69 subtract .69 from both sides
1.11= .23W divide both sides by .23
111/23 = W ≈ 4.826 pints
