GENETIC PROBLEM HELP?

In our consideration of Mendel's Results, we saw that zygous smooth, yellow peas mated with wrinkled, green peas gave rise to F1s that were smooth and yellow. The F2 peas also included smooth yellow plants, as well as the other three possible combinations of characters. A self-cross of one of the smooth, yellow plants of the F2 yielded 135 smooth, yellow and 47 smooth, green peas. What is the genotype of the plant that was self-crossed?