How do you find the conjugate of the following expression:

Here is my working, but I got bogged down by the algebra and think there must be an easier way.

How do you find the conjugate of the following expression:

Here is my working, but I got bogged down by the algebra and think there must be an easier way.

There is no need to get a common denominator - leave the first term as $x+iy$. Then for the second term, do as you did and multiply by $\frac{x-iy}{x-iy}$ to get it in the form $a+ib$.
Now you have two terms bein added of the form $(x+iy)+(a+ib)$, which you can re-write as $(x+a)+i(y+b)$. Now you can take the conjugate.