What are the real zeroes of x^3+ 6 x^2- 9x - 54?

This doesn’t make sense to me it’s supposed to be lcm ( least common multiple )

Ahome improvement store rents it’s delivery truck for $19 for the first 75 minutes and $4.75 for each additional 1/4 hour. if a customer rented the truck at 11: 10 am and returned the truck at 1: 40 pm the same day, what would his rental cost be?

Answer for 15 points (look at the image)