I don’t want to pay for PowerPoint, but whenever I open a PPT in Impress all of the equations just disappear. Being a maths teacher, this makes Impress a pretty useless substitute. Is this fixable?
M$ uses a different equation format than LO. You’ll have to reenter them. Insert>Object>Formula launches the equation editor.
What LO version do you use? Can you attach here your PPT file with those equations? (use Edit link in your question for it)
Maybe you can view the PowerPoint in your web browser and at the same time edit a copy in Impress to add in the equations. Possibly saving the PowerPoint equations as png or svg curves for a quick fix.
If the viewer allows exporting to pdf that would make a simple conversion to a presentation format.
There’s a great Libre Office extension for adding LaTeX equations when making your own slides (TexMaths » Extensions). Doesn’t help with opening other people’s slides though; I’ve not found a solution for that yet