[Orgmode] One unified .org to .html and .tex

[zwz]

I like org-mode.
I use it for taking notes and writing papers.

One problem pops up when I try to export one org file, which contains
some maths, to multiple formats, specifically html and tex. 

For tex, it is required to enclose the maths by $/$$; For html, there
is no need to use $/$$.

I just wondered if there is an unified way to generate those different
formats with one org file which still has good readability.

I guess there should be such a way.