Because the demand curve reflects buyers’ willingness to pay, we can also use
it to measure consumer surplus. Figure 7-2 uses the demand curve to compute
consumer surplus in our example. In panel (a), the price is $80 (or slightly above),
and the quantity demanded is 1. Note that the area above the price and below the
demand curve equals $20. This amount is exactly the consumer surplus we computed
earlier when only 1 album is sold.