#### Understanding

A proportional relationship is formally associated with an equation, and the slope of the line representing the proportional relationship is associated with the notion of unit rate.

### What to look for

This lesson focuses on the fact that a proportional relationship can be described by an equation of the form y = kx, where k is a positive constant, often called a constant of proportionality. The rate of change in y for a given unit in x will be constant for the points on the line.### Sample Assessment

Order the equations below in terms of steepest slope to least steep.

a. y = $\frac{2}{3}$ x

b. y = 2x

c. y = $\frac{1}{3}$ x

d. y = x

Answer: b, d, a, c