A company had inventory of 10 units at a cost of $20 each on November 1. On November 2, it purchased 10 units at $21 each. On November 6 it purchased 15 units at $25 each. On November 8, it sold 20 units for $54 each. Using the LIFO perpetual inventory method, what was the cost of the 20 units sold?

a. $395.
b. $480.
c. $375.
d. $510.
e. $520.

Answer: b. $480.