Answer: 75%
Explanation:
Yy seperate to yield two alleles "Y" and "y"
So, the cross of the two alleles:
"Y" X "y" by "Y" X "y"
F1 will be YY, Yy, Yy and yy
From the crossing, the dominant phenotype are YY, Yy, Yy; while yy is recessive.
Thus, the percentage of the offspring would have yellow peas are 3 out of 4 or 75%