# Understanding a current sensor circuit

I'm struggling to see how the output of this circuit is $$V_{0} = {I_{s} R_{s} R_{L}/{5k}}$$

My work thus far:

I understand the voltage into the base of the BJT is $$I_{s}R_{s}$$ I understand the voltage into the collector is Vin

Now what I am struggling to see is where the 5k term and the R_l term come from.

I see that the IsRs is the voltage across the the two leads of the opamp, this detects the current. Where the 5k and how Rl interacts I don't understand.

My guess would be the 5k is a result of voltage division.

Can someone guide me to understanding this circuit?