The answer would be 50%.
Let's make a Punnett square for this:
Let F - Freckles
f - no freckles
Father: Ff
Mother: ff (She has no freckles, meaning she does not have the dominant allele)
F f
f Ff ff
f Ff ff
The count would then be 2/4 with freckles and 2/4 without freckles. So the percentage of would be 50% with freckles and 50% without freckles.