Chapter 4 - Writing Linear Functions - 4.1 - Writing Equations in Slope-Intercept Form - Exercises - Page 179: 1

linear model

See p. 178 for this definition. note that When $y$ changes at a constant rate with respect to $x$, you can use $y=mx+b$ to model this where $m$ is the rate of change and $b$ is the initial value of $y$, aka the $y$-intercept.