The formula for finding the perimeter of a rectangle is P=2(l+w) where P is perimeter, l is the length and, w is width P=20 ft ,l=7ft but w=? P=2(l+w) 6ft=2w 20ft=2(7ft+w) 6ft/2=2w/2 20ft=14ft+2w 3ft=w 20ft-14ft=14ft-14ft+2w Therefore the width is 3ft