I need to simplify the following equation, by completing the square: $\frac{\left(x-z\right)^{2}}{2(u-s)}+\frac{(z-y)^{2}}{2(t-u)}$
As $\displaystyle\frac{\left(x-y\right)^{2}}{2(t-s)}+C$.
How can I do this? I can't seem to be able to deal with the fractions effectively when completing this square...