Coordination number of the metal...?

Question

Hi, i'm wondering if someone could help me with this question. very important that i know HOW you get the answer.

Indicated the coordination number of the metal and the oxidation number of the metal in each of the following complexes.

a) K4[Fe(CN)6] b)[Co(en)2(C2O40]+

c) [Cu(bipy)2I]I d) NH4[Cr(NH3)2(NCS)4]

Answer 1

 Part C: Coordination number is 5, (bipy is bidentate; which means 2) and only one I is inside the brackets. Therefore: 2(2) + 1 = 5

Oxidation number is 2 because of the two I atoms (-1), bipy is neutral (0) 

Therefore: x(Cu) - 2 + 0 = 0

x(Cu) = +2