Charles W. answered  03/23/20
AP/IB Certified and Experienced Microeconomics/Macroeconomic teacher
Perfectly Competitive firms produce where P=MC
Their MR = P as they have a horizontal MRDARP curve, so producing the Profit Maximizing quantity the Perfectly Competitive firm produces where P=MC or, at a price of $12 and a MC of $12.
 
     
             
 
                     
                    