What are the possible genotypes for this

Question

1.   The presence of Sickle Cell Anemia is also codominant. Individuals with genes for sickle cell anemia produce sickled Red Blood Cells whose Hemoglobin cannot efficiently carry oxygen or move easily through the blood vessels. Having the sickle cell trait means that half of their hemoglobin is normal the blood cells are correctly shaped, and half of the hemoglobin is misshaped making the blood cells look like crescent moons. Both alleles are expressed making this codominant inheritance.

 If Hb^SHb^S= sickle cell anemia; Hb^AHb^A= normal Hb; Hb^SHb^A= sickle cell trait (carrier)

a. What is the probability that a mother with sickle cell and a father who has the sickle cell trait will have a child with normal hemoglobin?

b. What are the possible genotypes for this cross?