The area is calculated by multiplying the length by width, the perimeter is calculated by adding up every side of the rectangle
Considering that we already are given the length of the floor we must divide 100 (the area) by 10 (the length) to get the width
100/10= 10 (the width)
The perimeter is equal to each side of the rectangle added together, a rectangle has two lengths and two widths
Therefore: 10 (the length) + 10 (the length) + 10 (the width) + 10 (the width) = 40
The perimeter is 40 feet