A cheeseburger from a fast food restaurant contains 19 g of fat, 20 g of carbohydrate, and 28 g of protein. how many kcal of energy does the cheeseburger contain? (the caloric values are: 4 kcal/g for carbohydrate, 9 kcal/g for fat, and 4 kcal/g for protein.) give the answer to 2 significant figures