Answer:
Ratio 1:2:1. That is, 25% lethality (PP), 50% platinum coat, 25% silver coat
Explanation:
When two heterozygous foxes are interbred, in every single birth, there is a
25% chance of having a fox homozygous for lethality (PP)
50% chance of having a heterozygous fox with platinum coat (Pp)
25% chance of having a homozygous fox with a silver coat (pp)