How do you find oxidation state of the metals of a complex with two coordination spheres?

For example suppose we have $\ce{[Pt(NH3)4][PtCl4]}.$ For the naming of this complex I need to know the oxidation number of the metals; let the oxidation number of first and second $\ce{Pt}$ be $x, y$ respectively, then one can obtain the equation $x+y=4$. How are we supposed to proceed further? Thanks.




Platinum can exist under two common oxidation numbers : $+2$ and $+4$. The most reasonable oxidation numbers are $x = y = 2$, because if the first $\ce{Pt}$ atoms is at $+4$, the other one is at zero, which is not reasonable. And if the first $\ce{Pt}$ atom is at zero, $\ce{[Pt(NH3)4]}$ would not be charged, which is contrary to the original formula.


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