Question

The model of monopolistic competition characterizes the market for plumbing services in a city. suppose that the market is in long-run equilibrium. for a typical plumbing firm, price:

Answer 1

For a typical plumbing firm, price: will equals average total cost. 
A market is considered to achieve equilibrium if the amount of Demand in the market is exactly the same as the amount of supply.
From this , we can conclude that if the market is in long-run equilibrium, the price of a product will always match the total cost.