you have to find a common denominator, in this case you can have 12 as that. Now you are going to multiply 11/4 by 3/3 and multiply 5/6 by 2/2. You should get 33/12 - 10/12, which is 23/12, or 1 11/12.
An irrational number is a number that has no pattern and has no end. For example 3 divided by 7 is an irrational number because of the lack of pattern and never-ending decimal.
