Final answer:
To completely fill the bathtub, it would take 8 minutes.
Step-by-step explanation:
To find the total time it takes to fill the bathtub, we need to calculate the rate at which water is being filled. The bathtub has a capacity of 58 gallons and initially has 18 gallons of water. Therefore, the amount of water that needs to be filled is 58 - 18 = 40 gallons.
Since the tub is filled in 5 minutes, we can calculate the rate of filling as 40 gallons / 5 minutes = 8 gallons/minute.
Therefore, it would take 8 minutes to fill the bathtub completely.