​Angela, Boris, and Carlos are dividing the​ vanilla-strawberry cake shown to the right using the​ lone-chooser method. The table to the right shows the value that each player places on each part of the cake. Suppose that Angela and Boris are the dividers and Carlos is the chooser. In the first​ division, Boris cuts the cake vertically through the​ center, with Angela choosing s1 and Boris s2. In the second​ division, Angela subdivides s1 into three pieces and Boris subdivides s2 into three pieces. Answer parts ​(a) through ​(d) below.