I think you should definitely go for the econ classes. The application literally has you upload a second resume listing ONLY your quantitative and second language abilities. That resume is going to look really sparse if you don't have any econ. This is just a guess, but of the classes you suggested, I would take econ first, then calculus or statistics. I don't know if I'd bother with algebra. I would also highlight your quantitative job responsibilities in your current profession. If you don't have any, I would try to get some, even if it's just using Excel on a daily basis.