Answer:
0.39 gallons per day.
Explanation:
We have been given that the Helvie family drinks 1.75 gallons of milk every 4.5 days. We are asked to find the unit rate of milk they drink per day.
To find the unit rate of milk they drink per day, we need to divide total quantity of milk by total number of days.



Therefore, the unit rate of milk they drink is approximately 0.39 gallons per day.