So first you want to convert both to have the same denominator.
5 1/2 - 3 3/4
To:
5 2/4 - 3 3/4
Now, to make it easier for me, I would convert both to an improper fraction.
5 2/4 -> 22/4
3 3/4 -> 15/4
So now you can just do,
22/4 - 15/4,
which is just 7/4.
This in mixed number form is 1 3/4.
