A store is selling two minutes of nuts in 20-ounce bags. The first mixture has 15 ounces of peanuts combined with five ounces of cashews, and costs $6.00. The second mixture has five ounces of peanuts and 15 ounces of cashews, and costs $8.00. How much does one ounce of peanuts and one ounce of cashews cost?