The planners in an agricultural community are considering enlarging the municipal water supply system in order to provide water to farmers. The potential maximum amount of additional water is 800 acre-feet. The following estimates have been made concerning the conversion of dry-farmed land to irrigation. The dry-farmed area now consists of 500 acres devoted to Crop A and 700 acres devoted to Crop B. One foot of water on Crop A will yield $200 additional profit per acre, and 1 foot of water on Crop B will yield $300 additional profit per acre. These estimates already take account of the cost of water. Find the best use of water using linear programming. How much higher could the cost of water rise before the plan becomes uneconomic?