A rectangular garden sits next to a house. Three sides of the garden are fenced, and the fourth side is the house. The length of the garden is 9 meters. A total of 21.5 meters of fencing is used. If w stands for the width of the garden in meters, which equation can be used to find its width?
A. 2w+9=21.5 C. 2w - 21.5 = 9
B. 2w + 18 = 21.5 D. 2w +21.5=18