It can be easier to factor out -1, so you have
.. = -1*((5 7/9) +(2 3/4))
.. = -1*(5+7 + 7/9 +3/4)
Both fractions can be expressed using a denominator of 9*4 = 36.
.. 7/9 = (7/9)*(4/4) = 28/36
.. 3/4 = (3/4)*(9/9) = 27/36
Sum the fractions by adding their numerators (when they have the same denominator).
.. 7/9 +3/4 = 28/36 +27/36 = 55/36
This is an improper fraction, so can be written as a mixed number
.. 55/36 = 36/36 +19/36 = 1 19/36
We can add this sum with the sum of the integers in our original problem
.. -1*(5 +7 +7/9 +3/4)
.. = -1*(12 +1 19/36)
.. = -1*(13 19/36)
.. = -13 19/36 . . . . . . . . the sum of your mixed numbers
