Test Tex
As you can see, you can easily use mathematical formulas within one line: \(\varphi\) . And display entire formulas.
$$\begin{aligned} \varphi &\Rightarrow \psi \\ \varnothing &\rightarrow A \end{aligned}$$$$ R_{\mu \nu} - {1 \over 2}g_{\mu \nu},R + g_{\mu \nu} \Lambda = {8 \pi G \over c^4} T_{\mu \nu} $$
And continue writing in mardown.