Both are correct. Either rule applied first will have the same result. Both rules will be used either way, and the order in which they are applied does not matter as long as they are applied correctly at each step.
The smallest one is -2/7 The largest one is 8/9 The difference between them is 8/9 - - 2/7 = 8/9 + 2/7 = 7*8/9*7 + 2*9/9*7 = 56 / 63 + 18 / 63 = 74 / 63 = 1 11/63
