Do I use this equation for a Friis law question
The gain of the first stage is included in NF1.

Noise figure is the noise factor converted to dB.

Noise factor for an amplifier is (SNRin)/(SNRout).  SNRout already includes the gain (plus additional noise contribution) of the first stage. 

This is why (other posts here have described this) it's important that the first amplifier or device in a chain have the lowest noise figure.