Microeconomics 6th Edition by Robert Hall, Shirley Kuiper, Marc Lieberman

Exercise 8

In Figure 1,a positive externality was corrected with a $30,000 subsidy paid to students. Draw a diagram to show that the total price paid by students,the total price received by colleges,and the equilibrium quantity of degrees would have been exactly the same if the $30,000 subsidy per student had been given to colleges instead.
Figure 1