# How to find distance of star using inverse square law

## Homework Statement

So i need to calculate the distance of some star the luminosity is 2 Lo and on earth its seen as .1 Lo

I=L/4piR2
F=L/4piR2

## The Attempt at a Solution

I found two formulas, but not sure what to use. The F is flux density, and I am not sure how I would use that to find the distance, flux density is magnetic field right? The other one I found, seems to fix more but not sure What I is. It says its the intensity so I am guessing its what the brightness is seen on earth so I=.1Lo ? Also how would you figure out the flux density?
thanks