Coat color in mice is incompletely dominant. Yellow and white-colored mice are homozygous, while cream-colored mice are heterozygous. If two cream-colored mice mate, what phenotypic ratio can we expect of their offspring?

Since it's incomplete dominance we know that all the traits are of course dominant.

That in mind we know that anything heterozygous will have two different traits, making the cream colored mice have a punnet square somewhat like this:

W Y

W WW WY

Y WY YY

Referring back to the yellow and white mice being homozygous (two of the same traits) we can gather from this punnet square the ratios for both.

WC = Cream colored = 50%

WW = White = 25%

YY = Yellow = 25%