Final answer:
An item with 12g carbohydrates, 9g fat, and 3g protein contains 141 Calories, calculated using the Atwater system values of 4 Calories/g for protein and carbohydrates, and 9 Calories/g for fat.
Step-by-step explanation:
To determine the number of calories in an item with 12g carbohydrates, 9g fat, and 3g protein, we use the Atwater system. This system assigns an average energy value per gram for each nutrient:
4 Calories/g for both protein and carbohydrates, and 9 Calories/g for fat.
So, the calculation would be as follows:
Carbohydrates: 12g × 4 Calories/g = 48 Calories
Fat: 9g × 9 Calories/g = 81 Calories
Protein: 3g × 4 Calories/g = 12 Calories
Adding these together:
48 Calories + 81 Calories + 12 Calories = 141 Calories.
This item contains a total of 141 Calories.