The average pea pod contains about 7 peas. the round shape of peas is determined by a dominant allele (r). if heterozygous round pea plants (r/r) are self-fertilized, what proportion of pods in the f1 plants will have all round peas?

Since the pea plans are heterozygous they contain one dominant and one recessive allele. When you extrapolate this out we find that 25% of the plants will be homozygous dominant, 50% will be heterozygous, and 25% will be homozygous recessive. So 75% of the plans will have round peas.