Slope is expressed as
change in the value of y/change in the values of x
slope = (y2 - y1)/(x2 - x1)
When x1 = 0, y1 = 17
when x2 = 1, y2 = 15
Slope = (15 - 17)/(1 - 0)
Slope = - 2/1
Slope = - 2
