Help Solving Equation: Notation Explained

[Derpotron]

I need some help solving the following:

The part that really trips me up is dealing with the notation. It would really help if you explained it as well.

 

[Derpotron]

Also it is in the context of finding the minimum mass of a star possible with the equation:

 

[jtbell]

If you can tell us where you found that equation (e.g. link to web page, or page reference to a book), it might help people who want to answer.

 

[Derpotron]

Oops! Sorry here it is: http://www.thphys.may.ie/staff/mshadmehri/AstroNotes/MINIMUM.pdf