The following table shows a proportional relationship between x and y. Write an equation to describe the relationship between x and y.

X Y

2 9

5 22.5

8 36

Understand that a relationship between two variables, x and y, is proportional if it can be expressed in the form y/x=k or y=kx. Distinguish proportional relationships from other relationships, including inversely proportional relationships (xy=k or y=k/x).