Answer: At $15, quantity demanded is 5,000 and quantity supplied is 2,500.
Explanation:
Equilibrium occurs at a point where quantity demanded for a good is equal to its quantity demanded.
As, can be seen from data, the quantity demanded = quantity supplied = 4,000 at $20.
At a price below this, that is at $15, demand for the good is greater than its supply.
At $15, quantity demanded is 5,000 and quantity supplied is 2,500.