Can't remember if PowerPoint has it internally but I would expect you can copy/paste from Word if not.
It can cope with most requirements, certainly in relatively small volumes such as quoting formulae in a report... A complex proof might be a bit more laborious, but last time I did anything like that it had to be hard-coded in LaTeX, way back at uni!
Libreoffice has the lot. Its free and is probably more useful than Microsoft office.
Expect microsoft to get cheesed off and either buy out the Document Foundation rights or make it difficult to integrate it with the microsoft products.
If they do choose the second then I'll move all my machines over to Linux.
Word, PowerPoint and Excel will let you enter equations (although Excel does not use them as a formula just yet). They all (from 2016 onwards I think) include, as an option, "ink to math" where you draw the equation with your mouse, or on a touchscreen, and it converts what you wrote/drew into an editable equation in the Equation Editor. Windows 10 has a "Math input panel" built in as well, that you can use with PowerPoint, Excel and Word - I'm not sure what other applications are "MathML" compatible?
