(External Battery) If i have Portable Charger that has a capacity of 50,000 mAh and
Battery is 185 Wh rated, which translates to 37 Ah (185 Watts x Hours = 185 Volts x Amps x Hours, 185 Volts x Amps x Hours/5 Volts = 37 Ah). Assuming the review is correct and the battery is 91% of rated capacity, that translates to 34 usable Ah. 34 Amps x Hours/6 Amps = 5.6 Hours.

So yes, you are correct.

NOTE: If it seems like the numbers are off (ex. 34/6 rounds to 5.7), that's because I rounded to 2 significant figures for the numbers I gave but kept all digits for the next steps of the calculations.