Okay, here we have this:
Considering the provided information, we are going to calculate the requested value, so we obtain the following:
Accordingly, since the amount of salt remains the same, then we have the following equality, where x represents the amount of water that must be added:
0.4(85)=0.17(x+85)
Let's solve for x:
34=0.17x+14.45
0.17x=34-14.45
0.17x=19.55
x=19.55/0.17
x=115
Finally we obtain that must be added 115 ounces of water to make a solution that is 17% salt.