A doctor places you on a strict diet of meats and bread. One ounce of bread provides 4 grams of protein and 12 grams of carbohydrates. One ounce of meat provides 5 grams of protein and 21 grams of carbohydrates. You must prepare this meal so that you consume 80 grams of carbohydrates and 20 grams of protein. How much bread and meat must you use to make this meal?
I don't know how to set up the systems of equation for this problem .