Answer: 4 hours
Explanation:
Let the number of hours that the repair take be represented by h.
Since the cost of Sam's car repair is $20 an hour plus $180 for parts and the total cost was $260, this can be formed into an equation as:
180 + 20h = 260.
20h = 260 - 180.
20h = 80
h = 80 / 20
h = 4
The repair took 4 hours