Suppose the three beachcombers from the previous problem decide to move to another beach...

Suppose the three beachcombers from the previous problem decide to move to another beach to collect shells and other items each morning to sell in their shops. They decide to divide the beach into three pieces so that each hunts in her own area. The beach they collect from is made up of 900 linear feet of sandy beach, 600 linear feet of rocky beach, and 300 linear feet of grassy beach. The preference of each beachcomber is given in the following table, where larger numbers indicate a greater preference.

If Elsa is the first divider and Sondra is the first chooser, find a proportional, envy-free division of the beach among the beachcombers.