In the Middle East water is a critical need. According to a population expert, there are 500 families of tribe A living in a small 300 square mile valley. This number is assumed to be the maximum number the water in the valley can support. A new tribe B invades the valley. According to studies each family fiercely defends a certain amount of territory and will not allow families of the other tribe to intrude. Suppose that a family of tribe A defends 1 square miles and a family of tribe B defends 3 square miles. Suppose further that tribe B uses twice as much water as tribe A. What is the maximum number of families of each tribe that can coexist in the valley.