There are 6 people going on an airplane trip.  They each have 5 bags of luggage.  Each of their bags weighs the maximum weight allowed, 50 pounds.  The airplane can hold a total luggage weight of 6000 pounds.  How many more bags at maximum weight can the plane hold?
Each person brought 5 bags * 50 pounds per bag = 250 pounds per person.
There are 6 people * 250 pounds per person = 1500 pounds of luggage on the plane.
The plan can hold 6000 pounds - 1500 pounds = 4500 pounds of luggage space left.
The plane can hold an additional 4500 pounds / 50 pounds per bag = 90 pieces of luggage.