What are the steps to solve this simple algebraic equation? This is the equation that I use to calculate a percentage margin between cost and sales prices, where $x$ = sales price and $y$ = cost price:
\begin{equation}
z=\frac{x-y}{x}*100
\end{equation}
This can be solved for $x$ to give the following equation, which calculates sales price based on cost price and margin percentage:
\begin{equation}
x=\frac{y}{1-(\frac{z}{100})}
\end{equation}
My question is, what are the steps involved in solving the first equation for $x$? It's been 11 years since I last did algebra at school and I can't seem to figure it out.
I'm guessing the first step is to divide both sides by $100$ like so:
\begin{equation}
\frac{z}{100}=\frac{x-y}{x}
\end{equation}
Then what? Do I multiply both sides by $x$? If so how to I reduce the equation down to a single $x$?

If you multiply an $x$ to each side, you will end up with $$ x \Big(\frac{z}{100}\Big) = x - y $$
However, an $ x $ still appears on both the left and right sides of the above equation. Reduce $ \frac{x -y}{x} $ to a single variable $ x $ by rewriting that expression as $$ \frac{x -y}{x} = \frac{x}{x} - \frac{y}{x} = 1 - \frac{y}{x} $$
Thus, $$ \frac{z}{100} = 1 - \frac{y}{x} $$
You may proceed accordingly to solve for $x$.
