[texhax] Math writing software for the Mac

[alberte]

Where can I purchase math software for the Macintosh OS 9?  I would like to
write and print my own math problems and equations. I everytime I open a
math book, I often ask myself, what type of software did they use to write
these math problems and equations with? I tell myself would¹nt be nice to
write my own problems and equations.

If you could please point in the right direction, I would really apprecate
it.

Thank You,
Albert Enriquez