A food sample contains 6 g of carbohydrate and 4 g of protein. How many kcal from carbohydrate and protein are in the sample?

40 calories

Explanation:

If we take average calorie per gram of protein and carbohydrate as 4 calories/gram.

Then, Calories from 4 g of protein = 4g * 4calories/g = 16 calories

Similarly, calories due to 6 g of carbs = 6 g * 4colries/g = 24 calories

Therefore, total calories = 16+24 = 40 calories