题目：A monopolist with cost functionC(Q)=20Qproduces in a market that can be segmented in two types of consumers with demandsQ1=20−0.5p and Q2=80−0.5p
Calculate the two-part tariffs which maximize profits of the monopolist.Compute welfare and compare with the social optimum.


       答案：
       T1= 100 + 20Q1 andT2= 4900 + 20Q2Suppose to simplify that there is only one consumer of each type:W^D=CS^D+PS^D= 0 + 5000 andW^C=CS^C+PS^C= 5000 + 0

没看懂答案，有大佬帮忙解释一下吗