laura is donating 2 boxes of books to the library. one box has a mass of 9 kilograms. the other box has a mass of 7 kilograms. what is the total mass of the 2 boxes in grams?
mass of first box + mass of second box = total mass of the two boxes
9 kilograms + 7 kilograms = 16 kilograms
16 kilograms = 16 × 1000 grams = 16 000 grams