5 3/7 - 2 1/5 -> 38/7 - 11/5 = 27/2 = 13 1/2

That's about as much as you can simplify this problem.
I hope this helps! :)
How do I find an equation that matches the quotient and the remainder?
The first thing you should do to answer the question is to take each of the amounts to percentages:
(1/4) * (100) = 25
(1/4) * (100) = 25
(5/12) * (100) = 41.67
(1/12) * (100) = 8.33
Adding all the amounts:
25 + 25 + 41.67 + 8.33 = 100%
answer
Yes, they ate the equivalent of a whole bread