Final answer:
Joe rented the bike for 4 hours. This was calculated by setting an equation, 18 + 5x = 38, representing the total cost and solving for the number of hours x.
Step-by-step explanation:
To find out how many hours Joe rented the bike for, we can set up an equation based on the information provided. Joe rented a bike for a flat fee of $18 with an additional cost of $5 per hour. The total amount Joe paid was $38.
Let's represent the number of hours Joe rented the bike as x. The flat fee is $18 and the hourly rate is $5. So, the total cost paid by Joe can be represented by the equation: 18 + 5x = 38.
To solve for x, subtract 18 from both sides of the equation:
5x = 38 - 18
5x = 20
Now, divide both sides by 5 to find x:
x = 20 / 5
x = 4
Therefore, Joe rented the bike for 4 hours.