Coordination Compounds

We are given the compound:
Fex[Fey(CN)6]3
and asked to find the values of x and y.
Step 1. Identify familiar Prussian blue-type compounds
Prussian blue and related compounds have the general formula:
Fe4[Fe(CN)6]3
This often corresponds to a mixed-valence compound containing both Fe2+ and Fe3+ ions.
Step 2. Match with the given general form
Given formula: Fex[Fey(CN)6]3
If we compare:
Fe4[Fe(CN)6]3
we identify:
x=4,‌‌y=1