(6 points) tabitha is ordered by her doctor to take 30 units of vitamin a, 24 units of vitamin d, and 16 units of vitamin e each day. there are three brands of supplements available with these vitamins. one brand x tablet contains 2 units of vitamin a, 1 unit of vitamin d, and 2 units of vitamin e. one brand y tablet contains 3 units of vitamin a, 2 units of vitamin d, and 2 units of vitamin e. one brand z tablet contains 4 units of vitamin a, 4 units of vitamin d, and 1 unit of e. how many tablets of each brand of supplement should she take to get the correct quantity of each vitamin?