In an nutrion experiment, a biologist wants to prepare a special diet for the experimental animals. Two food mixes A and B are available. If mix A contains 20% and mix B contains 10% Protein, What combination of each mix will provide exactly 20 grams of protein ? Let x be the amount A used and let y be the amount B used. Write a linear equation related x,y and 20. Graph this equation for x values between 0 and 200