A food product contains 15 g of carbohydrates, 5 g of protein and 4 g of fat. How many calories are in one serving of this product?

Answer: 116 calories of energy

Explanation:

A calorie is a non-standard unit of energy.

On combustion,

1 gram Carbohydrates = 4 calories,

1 gram protein = 4 calories,

1gram fat = 9 calories.

Therefore,

15 grams of carbohydrates = (15*4) = 60

5 grams of protein = (5*4) = 20

4 grams of fats = (4*9) = 36

Then add up: 60 + 20 + 36 = 116 calories of energy