This cache can help with several challenges. Rhyme Time Challenge, California Multi Cache Challenge, and maybe more.
This is a simple 2 stage multi. GZ should take you to a city light pole upon which you will find an alphanumeric designation. Convert the letter to its numeric value, add the four digits together then multiply by 3 to get X. Add X to 123 to get your North coords (N38 01.xxx). Subtract X from 317 to get your West Coords (W122 17.yyy).
Final coords check sum for ALL digits: 51