A firm faces the demand curve Q 20 08P and marginal cost M
     A firm faces the demand curve Q = 20 - 0.8P and marginal cost MC = 2.5Q.  If the firm cannot price-discriminate, what is the profit-maximizing price and quantity?  If the firm can practice perfect price discrimination, how many units will it sell? 
  
  Solution
a. since firms cannot price discriminate price and quantity will be
Q=20-0.8P HERE P=MC
MC=2.5Q
NOW,
Q=20-0.8(2.5Q)
SOLVING THIS Q=20/3
PUT Q=20/3 IN Q=20-0.8P TO GET THE PRICE
PRICE =16.66
b. since price discrimination is followed so price will be greater than the cost . so when p=mc quantity was 20/3
but here quantity will be more than 20/3.

