a. aabbccdd =x
x
x
= 1/256
b. AaBbCcDd =
x
x
x
= 1/16
c. AABBCCDD =
x
x
x
= 1/256
d. AaBBccDd =
x
x
x
= 1/64
e. AaBBCCdd =
x
x
x
= 1/128
Just remember that the probability of a heterozygote (Xx) = 2/4 or 1/2 and the probability of a homozygote XX or xx = 1/4