I need help answering this problem

Question

Carl the camel drank 15 1/4 quarts of water last week and 21 7/8 quarts of water this week. How many more quarts of water did Carl drink this week?

Answer 1

27 7/8 - 15 1/4 =

12 5/8 more this week = 12.625 more 12.625 quarts more this week

27-15 = 12

7/8 -1/4 = 7/8 -2/8 = (7-2)/8 = 5/8