Multiply the denominator by the whole number( 12 and 5) then add the numerator (so now it's -67/12). Do the same thing with 10 3/4 ( so now it's 43/4). Multiply 43/4 by 3 so you have a common denominator of 12. So now you have -67/12 + 129/12. Just do the math and then simplify. And by simplify I mean find a number that you can divide both the top and bottom of the fraction by to get the numbers as small as possible.