Punnett Squares — Examples & Diagrams

A scientist crosses two fruit flies to study the inheritance pattern of wing shape. The F$_1$ generation consists of 143 flies. After further research, it becomes clear that a single gene is responsible for wing shape and there are three distinct genotypes among the offspring in a 1:2:1 ratio. What are the genotypes of the original parents? Use Punnett squares to help you.