Calculate the mass of nickel(II) sulfate and the mass of water contained in 200. g of a 6.00% solution of nickel(II) sulfate

Answer 1

6% (is that w/w ?) means 6g NiSO4 in 100 g solution. That is 6g NiSO4/(6g NiSO4 + 94 g H2O).
So 200 g sample would contain twice those amounts.