136. Solving a chemistry problem

1 dm3 of waste water containing nickel was evaporated to dryness and after separation of the interfering impurities a precipitate of nickel dimethyl oximate was obtained. The washed precipitate was dissolved, 10 cm3 of a 0.01 M complexone III solution was added to titrate the excess of which 3.05 cm3 of a 0.01 M magnesium salt solution was used. Calculate mass concentration of nickel (mg/dm3) in waste water)