4.MD.A.3 Know and apply the area and perimeter formulas for rectangles in real- world and mathematical contexts. For example, find the width of a rectangular room given the area of the flooring and the length, by viewing the area formula as a multiplication equation with an unknown factor. All picture came from this website: https://www.k5learning.com/free-math-worksheets/fourth-grade-4/geometry/geometry-rectangles-area-perimeter