Suppose the MWTP in periods 1 (now) and 2 (one year from now) is given by P = 8-0.4q. Marginal extraction cost = $2. r = 10%. The available supply is 20 units. Suppose 13 units are consumed in period 1 and 7 units in period 2. Calculate the present value of the net benefits for the use of the resources. Show your work. Draw the graphs for both periods