Which expression represents the sum of 2/3m - 1 1/6 and 5/6m - 1 1/3

The expression before simplifying would look like:
(2/3m-11/6) + (5/6m-11/3)

Next you would group common terms and get:
(2/3m+5/6m)+(-11/6-11/3)

In order to combine these fractions. they need to have common denominators and the expression would become:
(2*2/3*2m+5/6m)+(-11/6-11*2/3*2)
(4/6m+5/6m)+(-11/6-22/6)

Now simplifying the expression, you would get:
9/6m+-33/6
or
9/6m-33/6