A market in Country B, which is a small economy, is described by the following supply and demand curves, respectively:

QS=P-5

QD=40-2P

where QSand QDare quantity supplied and demanded, and P is price.Suppose the world price is $10.The government in Country B places $3 tariff (per unit) on imported goods. What is the tariff revenue that the government collects?

a.

30

b.

6

c.

18

d.

45