Identify whether each of the following statements best illustrates the concept of consumer surplus, producer surplus, or neither.

a. i sold a jersey sweater for $31, even though i was willing to go as low as $22 in order to sell it.
b. i paid $36 for a used laptop last week. this week, the same store is selling laptops for $30.
c. even though i was willing to pay up to $61 for a used textbook, i bought a used textbook for only $51.