Arectangle bedroom floor has an area of 100 square feet and a length of 10 feet. what is the perimeter of the floor?

Do 100 divided by 10 and that is the answer to your question its 10 by the way

Since the area of the floor is 100 and one side is 10, then we should know that the other side is 10 because, 
10 * 10 = 100

So, since two sides are 10, than the other sides must be 10 too.

That gives 4 sides that all equal 10.

10+10+10+10= 40

So, the perimeter is 40.

Bwould be the answer