By Mike Moffatt
P = 80 - Q (Demand)
P = 20 + 2Q (Supply)
Given the above demand and supply equations for widgets, find the equilibrium price and quantity.
Answer: To find the equilibrium quantity, simply set both of these equations equal to each other.
80 - Q = 20 + 2Q
60 = 3Q
Q = 20
Thus our equilibrium quantity is 20. To find the equilibrium price, simply substitute Q = 20 into one of the equations. We will substitute it into the demand equation:
P = 80 - Q
P = 80 - 20
P = 60
Thus our equilibrium quantity is 20 and our equilibrium price is 60.
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