A laundromat can buy two types of washing machines, a top-loading model and a front-loading model. The top-loading model can wash 50 items per day while the front-loading model can wash 75 items per day. The top-loading model consumes 85 kWh per day while the front-loading model consumes 100 kWh per day. The laundromat must be able to wash at least 5000 items per day and has available 7000 kWh per day. Since the top-loading machine are harder to use, at most 40% of the machines can be top-loading. Further, at least 10 machines should be front-loading. How many of each machine should the laundromat buy to minimize the total number of washing machines?