Adding formulas / equation created by latex text.
To be able to do this, one first has to add MathJax add on into the weebly platform. Use Add Apps in the editor.
See: https://drive.google.com/drive/folders/0B5xdRARSG1JiQmV1ZjJiX2JxSlk
Once that is done, latex can be written on any page.
Properly formatted output will be seen (rendered) when viewing the page (but not in the edit window).
$$f(n) = \begin{cases} n/2, & \mbox{if } n\mbox{ is even} \\ 3n+1, & \mbox{if } n\mbox{ is odd} \end{cases}$$