calculating volume of EDTA

6. A solution contains 1.694 mg of CoSO4 (155.0 g/mol) per milliliter. Calculate
(i) the volume of 0.08640 M EDTA needed to titrate a 25.00-mL aliquot of this solution.
(ii) the volume of 0.009450 M Zn2+ needed to titrate the excess reagent after addition of 50.00 mL of 0.008640 M EDTA to a 25.00-mL aliquot of this solution.
(iii) the volume of 0.008640 M EDTA needed to titrate the Zn2+ displaced by Co2+ following addition of an unmeasured excess of ZnY2- to a 25.00-mL aliquot of the CoSO4solution.
The reaction is Co2+ + ZnY2- CoY2- + Zn2+