In pea plants, round (R) seeds are dominant to wrinkled (r)…

In pea plants, round (R) seeds are dominant to wrinkled (r) seeds. A parent homozygous for round seeds is crossed with a parent homozygous for wrinkled seeds. If a plant from the F1 generation is backcrossed to the parent with wrinkled seeds, what is the proportion of the offspring that will have wrinkled seeds? (Assume 100% penetrance and complete dominance)