Answer:
Answer in explanation :)
Step-by-step explanation:
Ok so if they're both brown-eyed and yet they have a blue-eyed baby that means blue eyes is a recessive gene. In a punnett square it would look kinda like the one I sent as a file. Except that both parents would have Bb genes. This would mean it would be in each quadrant:
BB Bb
Bb bb
So for the kid to be blue eyed they must have the genetics of the bottom right square. Hope this helps :)