Lucy drank 8 1/2 cups of water and Bella drank 5 3/8 cups of water. how much did they drink altogether

13 and 7/8

Step-by-step explanation: The word "altogether" in the question is a key word that tells us that we want to add.

To add mixed numbers, first add the fractions.

Since 1/2 and 3/8 are unlike fractions, we first need to

find a common denominator, which in this case is 8.

So we multiply the numerator and denominator of

1/2 by 4 to get 4/8 and 3/8 already has 8 in the denominator.

Now we can add the like fractions, 4/8 + 3/8, to get 7/8.

Next we add the whole numbers, 8 + 5 is 13.

So altogether, Lucy and Bella drank 13 and 7/8 cups of water.