We are given the following function
[tex]C(t)=87t+32[/tex]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
[tex]y=mx+b[/tex]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.