Calculate the molarity of the Ni2+ and Zn2+ in the original solution.?

a 50.00mL solution containing a mixture of Ni2+ and Zn2+ was treated with 25.0mL of 0.0452 M EDTA to bind all metal. The excess unreacted EDTA required 12.4mL of 0.0123 M Mg2+ for complete reaction. An excess of the reagent 2,3-dimercapto-1-propanol was then added to displace EDTA from zinc. Another 29.2mL of Mg2+ were required for reaction with liberated EDTA. Calculate the molarity of the Ni2+ and Zn2+ in the original solution.