240 kC
The answer to this question depends upon the values you use for the number of kilocalories per gram of fat, protein, and carbohydrate. Nutritional charts indicate the protein and carbohydrates have 4 kilocalories per gram and fat has 9 kilocalories per gram. The figures obtained via a Bomb Calorimeter are higher with protein having 5.65 kilocalories, carbohydrates at 3.94 kilocalories per gram, and fat at 9.44 kilocalories per gram. So, I'll answer this question using both values. Regardless of what values you use, the result is simply the sum of the products times calories per nutrient.
Using common calorie figures.
15 * 4 + 1 * 9 + 42 * 4 = 60 + 9 + 168 = 237
= 240 kC (to 2 significant figures)
Using bomb calorimeter figures.
15 * 5.65 + 1 * 9.44 + 42 * 3.94 = 84.75 + 9.44 + 165.48 = 259.67
= 260 kC (to 2 significant figures)
