Am 17.05.2015 um 22:54 schrieb Troy Henderson <thenders@gmail.com>:

I updated pstoedit, and it fun ctions as expected.

This is not a MetaPost question but rather a ConTeXt question:  How do I use Arev Bold (Sans) in ConTeXt?

Use the DejaVu fonts which are like Arev Sans a extended version of Bitsream Vera.

\setupbodyfont[dejavu]

\starttext

\input knuth

\ss\input knuth

\startformula
c^2 = a^2 + b^2
\stopformula

\stoptext

Wolfgang