An 8-ounce glass of low-fat chocolate milk contains 160 kilocalories (kcal) and 8 grams of protein. what percent of the kcal in the milk comes from protein?

Protein has 4 calories per gram. Since this glass of chocolate milk has 8 grams of protein, it has 32 (4*8) calories which originate from protein. Given that the total amount calories contained in this glass are 160, the percentage of calories coming from protein is (100*32) / 160 = 20%.