If one parent has brown eyes and the other has blue whats the percent that the child will have blue eyes

This question either isn't complete or it is very open ended. There is so many possibilites. We don't know which is the dominant allele, we don't know if it is hetero or homozygous. If both parents are homozygous then the baby has a zero pecent chance of being clue since it will have incomplete dominance. If the brown eye is dominant then it will have a 100 percent if the browned eye parent is homozygous. But a 50 percent chance if its heterozygous. Same for the blue eyeed parent. Any of these should satisify this question if this is the only part of the question