The slope is the ratio of car washes to the number of days since Auto Spa opened; and the y-intercept is the number of car washes on the day the Auto Spa opened.
Explanation:
This line of best fit is in slope intercept form: y=mx+b, where m is the slope and b is the y-intercept.
In this equation, m corresponds with -0.12 and b corresponds with 31.76.
The slope is the ratio of change in y to change in x. The y-coordinate of each point represents the number of car washes and the x-coordinate represents the number of days since Auto Spa opened; the ratio of change in y to change in x is then the ratio of the number of car washes to the number of days since Auto Spa opened.
The y-intercept is the point where the data crosses the y-axis; at this point, and all on the y-axis, the x-coordinate is 0. In this problem, the x is the number of days since Auto Spa opened; if it is 0, this means 0 days since it opened, which would be its opening day. Thus the y-intercept is the number of car washes on opening day.
