Answer :
Assume B is white, b is recessive brown
Bb x Bb
B b
B BB Bb
b Bb bb
Genotypes: BB, Bb, bb
Phenotypes: 3 white, 1 brown
Bb x Bb
B b
B BB Bb
b Bb bb
Genotypes: BB, Bb, bb
Phenotypes: 3 white, 1 brown