A pharmacy mixes different concentrations of saline solutions for its customers. The pharmacy has a supply of two concentrations, 0.4% and 4%. The function y=((100)(0.4)+x(0.004))/(100+x) gives the concentration of the saline solution after adding x milliliters of the 0..4% solution to 100 milliliters of the 4% solution. How many milliliters of the 0.4% solution must be added to the 4% solution to get a 0.85% solution?
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