#### Answer

a) See below.
b)0.25
c)0.75

#### Work Step by Step

a) We have 4 different outcomes: blue-blue, blue-brown, brown-blue, brown-brown.
b)We know that $probability=\frac{number \ of \ good \ outcomes}{number\ of\ all\ outcomes}$ and that we have 4 possibilities out of which 1 (blue-blue) is good, hence $probability=\frac{1}{4}=0.25.$
c)We know that $probability=\frac{number \ of \ good \ outcomes}{number\ of\ all\ outcomes}$ and we also know that if at least 1 allele is brown then the ye is brown, hence we have 4 possibilities out of which 3 (blue-brown, brown-blue, brown-brown) are good, hence $probability=\frac{3}{4}=0.75.$