I would like to change the font "thickness" of the font in math mode. I already tried to find a similar method like \DeclareMathSizes but i didn't find something.

edit:
I want to use - if possible - in math mode a font with serifs that is not as thin as the "typical" one. Since I'm trying to include latex formulas in powerpoint I need them for a presentation and, thus, a thicker font would be great.
P.S.: To the best of my knowledge, I'm using pdflatex ;-)

Thanks for your help


Question: "Find ten apples and oranges" Do I find 10 or 20?
Answer: And can be both a distributive coordinator and a joint coordinator. So, for example, if a subject includes a distributive and, then the predicate applies equally and distinctly to both noun elements:


  John and Mary live in London


means 


  John lives in London and Mary lives in London.


A subject including a joint and cannot be expanded in this way. So,


  John and Mary are a happy couple


is incoherent as 


  John is a happy couple and Mary is a happy couple.


Often, however, there is no way to reliably interpret if the and is a distributive coordinator or a joint coordinator. For example:


  John made cheese and cucumber sandwiches.


Did all the sandwiches consist of both cheese and cucumber (joint coordination) or did he make cheese sandwiches and also make cucumber sandwiches (distributive coordination)?

The OP's sentence Find ten apples and oranges is ambiguous in the same way.

There is a brief discussion of distributive / joint coordination in The Handbook of English Linguistics (Aarts).