We are given the following function
Where C represents the total cost of purchasing t tires and oil change.
Recall that the standard form of slope-intercept form is given by
Where m is the slope and b is the y-intercept.
Comparing the standard form with the given function we see that
slope = m = 87
y-intercept = b = 32
Therefore, the number 87 in the function represents the slope that is the cost per tire purchased.