Normally pigmented: P (dominant)
Albino: a (recessive)
a) Two normally pigmented parents have five children, four normally pigmented, one albino.
If parents are normally pigmented and had an albino child, both need to be heterozygous dominant for normal pigments
Pa x Pa =( PP, Pa, aP, aa) Those are all the probabilities, left to chance.
b) A normally pigmented male and an albino female have six children, all with normal pigmentation.
The albino is a recessive character so, an albino person, it will always aport the albino allele.
If none of the children is albino, you could say the male is heterogygous or not.
PP (male) x aa (female) = (Pa, Pa, aP, aP) phenotypically all will be normally pigmented.
or
Pa (male) x aa (female) = (Pa, Pa, aa, aa) Because of chance, it could be this way but never appear the aa combination of alleles.
c) A normal male and an albino female have six children, three with normal pigmentation, three with albinism.
Now, you have a male with heterozygous alleles.
Pa (male) x aa (female) = (Pa, Pa, aa, aa) Those are all the probabilities, left to chance.