Knowing that:
1 qt = 0.25 gallons
Then,
85 qt = 85*0.25 gallons
85 qt = 21.25 gallons
21.25 gallons is the same as 21 gallons + 0.25 gallons, and since 0.25 gallons = 1 qt:
21.25 gallons = 21 gallons + 1 qt
Finally,
85 qt = 21 gallons 1 qt
Answer:
85 qt = 21 gallons 1 qt