John is a salesman for the local car dealership. He can divide his 40-hour work week between talking to customers that walk in the door and calling possible prospects. Let W be the number of hours each week he spends on walk-ins, and let P be the number of hours spent on calling prospects. In a typical week, the number of cars John sells depends on the time he spends on these tasks as follows: N(W, P) = 09W - 0.01W2 = 0.5P. John earns a bonus of $1,000 for each car he sells. How should he divide his time between walk-ins and calling prospects?