please answer each letter

Look at the table below. Instructions: Enter your answers as a whole number. a. What is the total surplus if Bashir buys a unit from Chander? $ b. What is the total surplus if Barb buys a unit from Chaaya? $ c. What is the total surplus if Bashir buys a unit from Chad? d. If you match up pairs of buyers and sellers so as to maximize the total surplus of all transactions, what is the largest total surplus that can be achieved