The equation for this scenario is y=5+0.5x. To identify the slope of the line, look to the variable "x", that causes the slope of the line. You do not know how many cookies are going to be sold at 50 cents a piece, so you put "x". The slope is 0.5. The y-intercept of the line is the fixed variable that you start with. In this case, it is 5, because that is what you sold the cookies at before, and that time period is done. The y-intercept is 5.