This is some steps into the equation

But I am having difficulty simplifying this

$\displaystyle x- \frac{3}{2}x = -8\frac{1}{2}$

The author shows the above simplified as

$\displaystyle -\frac{1}{2}x = -8 \frac{1}{2} $

Can you adjust assume X = 1 and do $\displaystyle 1 - 3/2 $ thus equaling $\displaystyle -\frac{1}{2}x$?