Formula for Filtered Time Average

I used =TEXT(G2-G3,"[h]:m") in Office 2016 to calculate the delivery time between stages for multiple orders. Now I have filtered the various stages of the order delivery to only show deliveries between two cities. I want to calculate the average delivery time (hours, minutes) per city, but all of the formulas i have tried--subtotal, average, averageif, averagea, averageifs, vlookup--have all failed. How do I calculate the average time (hours: minutes) for a column of filtered times (calculated by =TEXT(G2-G3,"[h]:m")? Been working on this for several days and would desperately appreciate some help, thank you.