The accompanying table shows the supply and demand schedules for used copies of the first edition of this textbook. The supply schedule is derived from
offers at amazon.com. The demand schedule is estimated.

a. Calculate consumer and producer surplus at the equilibrium in this market.

Now the second edition of this textbook becomes available. As a result, the willingness to pay of each potential buyer for a second-hand copy of the first
edition falls by $20. In a table, show the new demand schedule and again calculate consumer and producer surplus at the new equilibrium.