One slice of cheese pizza contains 290 Cal, 15 g of protein, 9 g of fat, and 39 g of carbohydrates. One-half cup of gelatin dessert contains 70 Cal, 2 g of protein, 0 g of fat, and 17 g of carbohydrates. One cup of whole milk contains 150 Cal, 8 g of protein, 8 g of fat, and 11 g of carbohydrates. (Source: Home and Garden Bulletin No. 72, U.S. Government Printing Office, Washington, D.C. 20402)
a) Write 1 × 4 matrices P, G, and M that represent the nutritional values of each food.
b) Find 3P + 2G + 2M and tell what the entries represent.