A brown-eyed man married a blue-eyed woman. The child has blue eyes.

A brown-eyed man married a blue-eyed woman. The child has blue eyes. What are the genotypes of the father’s eye color? Mother? The child has?

First you need to determine which eye color belongs to the dominant gene and which is the recessive one. Since the child has blue eyes, it can be concluded that blue dominates over brown, because if blue were recessive, then both parents would be blue-eyed, and the father has brown eyes. Means: A-blue, a-brown. When crossing parental genotypes, we get:
A_ x aa
Aa
The mother’s genotype can be either AA or Aa.