Normal text and cases

Question

I'd would be glad if anybody told me how to put a piece of normal text in display mode the way it is marked by the red circle on the photo

So it is aligned as normal text but next to it there is an equation block.

Answer 1

One way (as starting point) can be use minipage with width determined by ˙\linegoaloflinegoal` package in which you insert your equation:

\documentclass{article}
\usepackage{mathtools}
\usepackage{linegoal}
\usepackage{lipsum}


\begin{document}
\lipsum[66]
\[
\text{I}% "and"
\begin{minipage}{\linegoal}
    \begin{equation}    
        \begin{rcases}
        A = first\ line    \\
        B = second\ line
        \end{rcases}
    \end{equation}
\end{minipage}
\]
\lipsum[66]
\end{document}

In above MWE (Minimal Working Example) I left to you to write correct equation and write text in Cirilic:

where "I" transcripted to Cyrillic letter mean "and".

For further help you need to provide example of MWE, a small but complete document (similarly as is my MWE) which will show what you tray so far.

Answer 2

(Ab)using flalign

\documentclass{article}
\usepackage{amsmath}

\begin{document}
\noindent
text text text
\begin{flalign}
\text{and}&&
\left.
\begin{aligned}
L &= \frac{\mu_0}{\pi}\log\frac{a-r}{r}=4\cdot10^{-7}\log\frac{a-r}{r}
     \quad\left[\frac{\mathrm{H}}{\mathrm{m}}\right]
\\[2ex]
L &= \frac{\mu_0}{2\pi}\log\frac{r_2}{r_1}=2\cdot10^{-7}\log\frac{r_2}{r_1}
     \quad\left[\frac{\mathrm{H}}{\mathrm{m}}\right]
\end{aligned}
\right\},
&&
\end{flalign}
text text text
\end{document}

Answer 3

I wouldn't use “and” in that context, because the brace already implies it.

\documentclass{article}
\usepackage{amsmath,mathtools}

\usepackage{showframe} % just for the example

\begin{document}

\begin{equation}
\hspace{-0.5em}
\text{and}
\hspace{10000pt minus 1fil}
\left.
\begin{aligned}
L &= \frac{\mu_0}{\pi}\log\frac{a-r}{r}=4\cdot10^{-7}\log\frac{a-r}{r}
     \quad\left[\frac{gn}{m}\right]
\\[2ex]
L &= \frac{\mu_0}{2\pi}\log\frac{r_2}{r_1}=2\cdot10^{-7}\log\frac{r_2}{r_1}
     \quad\left[\frac{gn}{m}\right]
\end{aligned}
\right\},
\hspace{10000pt minus 1fil}
\end{equation}

\end{document}