pls help to explain those two and what formulae we should use for each. ( I thought the answer for first one is b) 4 and the second is also b) increases by $3, because (5-2)+(1-0)=4 also same with the second question is (4-3)+(2-0)=3).

Jay and Amile go trick-or treating. Initially, Jay gets Skittles and Amile gets a Kit-Kat. Neither of them has to pay anything for this candy. Their valuation of each good is given in the table below. They decide to trade. What is the new tota' economic surplus? 1) Anna and Elsa are in the school cafeteria eating lunch. Anna has a peanut butter sandwich and Elsa has a turkey sandwich. Their valuation of each good is given in the table below. They decide to trade. How is total economic surplus affected by their trade? Peanut butter sandwich value Turkey sandwich value A) It is unchanged B) It increases by $3 C) It decreases by $3 D) It increases by 56 E) It decreases by $6