The problem is: X/2 - 2x + 2y/ 4y

It says to express as a single fraction in the simplest form. Do I need to find a common denominator like a regular fraction without X's or y's?

First of all - you have written a function with 3 variables, namely, X (caps), x and y. I am assuming here you meant 'x' and 'X' are same. You need write those consistently.

Second, as written, the expression you wrote is equivalent to:

\(\displaystyle \frac{X}{2} - 2x + \frac{2y}{4y}\)

I have a suspicion that is not correct!

Please re-write your expression using brackets (grouping symbols) so that we can see your problems correctly.

In addition, please show us what you have tried - so that we know where to begin to help you.