To find the amount of export/import of bikes, we need to find the market equilibrium price and quantity. We can do this by setting the demand equation equal to the supply equation and solving for p:
Qd = Qs
121 - 3.7p = 17 + 2.2p
104 = 5.9p
p = 104/5.9 = 17.66
This is the market equilibrium price. To find the market equilibrium quantity, we can substitute this price into either the demand or supply equation:
Qd = 121 - 3.7 * 17.66 = 60.86
Qs = 17 + 2.2 * 17.66 = 56.14
Since the world price of bikes is 20, we can see that it is lower than the market equilibrium price in the domestic market. At the world price of 20, the demand for bikes in the domestic market will be greater than the supply. This means that there will be an excess demand for bikes, and the market will import bikes from other countries to meet this demand.
The amount of import can be calculated as the difference between the demand and supply at the world price of 20:
Qd = 121 - 3.7 * 20 = 82
Qs = 17 + 2.2 * 20 = 37
Import = Qd - Qs = 82 - 37 = 45
So the amount of import in this market is 45 bikes.
Alternatively, if the world price were higher than the market equilibrium price in the domestic market, there would be an excess supply and the market would export bikes to other countries. The amount of export would be the difference between the supply and demand at that higher world price.