In peas, the color yellow (y) is dominant to the color green (y). how many of the four possible outcomes are yellow?

It depends on the situations. In the first situation, a Yy gene crosses with a Yy gene. 3 out of 4 of the outcomes have a capital Y in them, meaning that they have a dominant yellow allele. The bottom-right box has two lower-case y's, so it will be green. In the second situation, a YY gene crosses with a Yy gene. Here, all 4 out of 4 of the outcomes have at least one capital Y, so they will all be yellow. Hope that helps!