get a common denominator of 12
-8 3/12 + 5 8 /12
subtract and take the sign of the larger
8 3/12 - 5 8/12
we need to borrow
8 + (12/12+3/12) - 5 8/12
8 15/12 - 5 8/12
2 7/12
the sign of the larger is negative
so -2 7/12
