A 50.0 mL sample containing Ni+2 was treated with 25.0 mL of .050 M EDTA to complex all of the Ni+2 and leave some excess EDTA in solution. the excess EDTA was then titrated with .050 M Zn+2, requiring 5.00 mL to reach equivalence point. What was the concentration of Ni+2 in the original solution? (EDTA forms complexes with metals in a 1:1 stoichiometry)