Hello Maria,

The problem implies that we want to write the (average) amount of natural sweeteners consumed per person as a function of time. Let y represent the (average) amount of natural sweeteners consumed per person (in pounds), and let x represent the time measured in years since 1990. That is, x = 0 represents 1990. If y is a linear function of x, then we can use the slope-intercept form **y = mx + b (**where **m is the slope** and **b is the y-intercept) **to write the function.

The **slope can be interpreted as the rate of change of y with respect to x**, which in this case means the change in consumption of natural sweeteners per year. The statement that consumption has decreased by 0.6 pounds per year tells us that the **slope is** **m = -0.6 **Also, the **y-intercept is the same as the y-value of the function when x = 0**. (In our case, that means time 0, that is, 1990.) Therefore the **y-intercept is b = 133**. Hope that helps! Let me know if you have any further questions.

William