Well to find the area of a rectangle you have to go length times width.
If the area is 900 and the length is 100. You already have a basic equation.
100 times X = 900.
X will equal the width.
To get the answer, you have to reverse this equation so you divide the area by the length.
900 divided by 100. That comes to 9.
The width of the rectangle is 9. Hope this helped!:)
