Peas heterozygous for three independently assorting genes were intercrossed. (example cross:

Peas heterozygous for three independently assorting genes were intercrossed.

(example cross: Aa Bb Cc x Aa Bb Cc )

What proportion of the offspring will be homozygous for one gene and heterozygous for the other two?

(hint: apply binomial expansion equation. Please explain.