Renting a car costs $30 per day, or $600 per month. Renting daily is cheaper for a few days, but after how many days are the two options equal (after which renting monthly is cheaper)?

20 days

Step-by-step explanation:

Renting a car costs $30 per day.

y = 30x

Renting a car costs $600 per month

y = 600

Set the two equations equal to each other.

30x = 600

(30x)/30 = (600)/30

x = 20

After 20 days, the two options have an equal cost.