one parent has brown eyes the other has blue eyes, if they have a child what is the percent that it will have brown eyes? blue eyes?

Since brown (B) is dominant over blue (b), the genotype of the brown-eyed parent can either be BB or Bb. The blue-eyed parent must be bb.

If there is any evidence of blue-eyed sibs or parents for the brown-eyed parent, then that genotype would be Bb. In that case, by chance half of the children will be Bb and half will be bb.

Those are the genotypes, so what are the phenotypes (physical traits)?