According to research at the Great Swamp in New York, the percentage of fish that are intolerant to pollution can be estimated by the function P(W, R, A) = 48 - 2.43W - 1.81R - 1.22A, where W is the percentage of wetland, R is the percentage of residential area, and A is the percentage of agricultural area surrounding the swamp.

(a) Use this function to estimate the percentage of fish that will be intolerant to pollution if 5 percent of the land is classified as wetland, 15 percent is classified as residential, and 0 percent is classified as agricultural.
(b) What is the maximum percentage of fish that will be intolerant to pollution?
(c) Develop two scenarios that will drive the percentage of fish that are intolerant to pollution to zero. 

(d) Which variable has the greatest influence on P?