Answer:
Jim will have to buy 6 carpets of 200 ft².
Step-by-step explanation:
This is a case of calculating areas, first we have to know much area have each one of the rooms and then multiply it by 4 to cover all the rooms. To calculate an square area we multiply the distance of each side, this is:

One room has 287 ft².
Now we can calculate the area of the four rooms:

The total area of the four rooms is 1,148 ft².
Now we can calculate how much carpet we need to cover all the area, this is a case of a division, this is:

Now we have that we need 5.74 carpets of 200 ft², but the carpets are sell by integers, so Jim will have to buy 6 carpets of 200 ft².