Formulate and solve by hand using the Simplex Tableau. A company manufactures raspberry and blueberry sports drinks. The net profit per litre of raspberry drink is $3 and $6 per litre of blueberry drink. The company wishes to control the production rates of the two drinks within a certain band. The production rate of raspberry drinks should not exceed the production rate of blueberry drinks by more than 4 litres per minute, and the production rate of blueberry drinks should not exceed the production rate of raspberry drinks by more than 1 litre per minute. How many litres per minute of each drink should the company produce to maximize profits?