A commercial pear grower must decide on the optimum time to have fruit picked and sold. If the pears are picked now, they will bring 30? per pound, with each tree yielding an average of 60 pounds of salable pears. If the average yield per tree increases 6 pounds per tree per week for the next 4 weeks, but the price drops 2? per pound per week, when should the pears be picked to realize the maximum return per tree? What is the maximum return?