Wanchen has been hired to make snacks for a party. She has $54.00 to spend on ingredients. The ingredients for a vegetable plate cost $6.00, and the ingredients for a fruit plate cost $9.00. Wanchen has been asked to make no more than 4 fruit plates and no more than 6 vegetable plates. If Wanchen makes a profit of $5.75 for each fruit plate and $3.20 for each vegetable plate, how many vegetable plates should she make in order to maximize her profit?