differential amplifier
V2-V1 in your equation is the voltage across the current sense resistor R9. Rf/Ri is the gain, which (from your schematic) is 166/1. So the output voltage will be 0.03 * 166 which is 4.98V

To set a gain of 100, you can use 1000K resistors in place of the the 166K, and replace the 1K with 10K as you suggest.