# Use split to align equation and the operation which is applied

I want to display an equation on multiple lines. I know that I can align multi-line equation with the split environment. But now I would like to align the equation by the equal sign and display at the end of the equation the applied operations like this:

3 * x = 15 | /3
x     = 5


So far I have this code, but I don't know which is the best way to align the applied operation.

$$\begin{split} U_{VS1} - I_{C} \cdot R_{1} &= U_{VS1} - I_{C} \cdot R_{2} \quad \lvert \, + I_{C} \cdot R_{2} \\ \end{split}$$


split is the wrong tool for this: you need alignedat.

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{alignedat}{2} &U_{VS1} - I_{C}R_{1} &&= U_{VS1} - I_{C}R_{2} \quad \lvert {} + I_{C} R_{2} \\ &U_{VS1} &&= U_{VS1} \end{alignedat}

\end{document}


The trick is to have two pairs of right-left columns, using only the left aligned ones.