First of all assume you have 1 litre of sol'n
so you have 2.25x10^-5 mols of Fe3+ and 0.50 mols of SCN-
The Fe3+ is the limitting reagent so you can only get 2.25x10^-5 mols of FeSCN2+.
(Imagine you are making Ham and cheese sandwhiches. You have 20 pieces of cheese and 5 pieces of ham. You...