The slope of the phone plan is 1, representing the increase in cost per extra minute used. The y-intercept is 40, representing the fixed cost of the phone plan. ;
The slope of Marge's phone plan is 1, indicating a $1 increase in cost for each extra minute used. The y-intercept is 40, representing the fixed monthly cost of the plan without any extra minutes. This illustrates a clear linear relationship between the number of extra minutes used and the total monthly cost.
;