-5/12 - 1/4 + 3/12
To add fractions, they must all have the same denominator.
Change the -1/4 to twelfths:
-1/4 = -3/12 .
So now the problem is
- 5/12 - 3/12 + 3/12
Notice that the -3/12 and the +3/12 knock each other out,
and all you're left with is
- 5/12 .