You can convert them all to decimal, or use some other common denominator, like 132.
7/11 = 84/132
5/6 = 110/132
2/8 = 33/132
Your ordering is 2/8 (=1/4), 7/11, 5/6.
You really don't have to do much conversion. You can look at them like this
7/11 = a little more than 5.5/11, which is 1/2
5/6 = almost 1, much more than 1/2, which is 3/6
2/8 = well under 1/2, which is 4/8
So, you have numbers that are "a lot less than 1/2", "a little more than 1/2", "almost 1". The ordering should not be hard to figure out.
7/11 = 84/132
5/6 = 110/132
2/8 = 33/132
Your ordering is 2/8 (=1/4), 7/11, 5/6.
You really don't have to do much conversion. You can look at them like this
7/11 = a little more than 5.5/11, which is 1/2
5/6 = almost 1, much more than 1/2, which is 3/6
2/8 = well under 1/2, which is 4/8
So, you have numbers that are "a lot less than 1/2", "a little more than 1/2", "almost 1". The ordering should not be hard to figure out.