19. The perimeter of a rectangle is 26 meters. The difference between the length and the width is 5 meters. Find the width.

Call the lenght L.  Since the length is 5 more than the width, the width is L - 5.

Perimeter = (L) + (L - 5) + (L) + (L - 5)  =  26

Simplifying:  4L - 10  =  26

                         4L  =  36

                           L  =  9                          W  =  L - 5  =  9 - 5  =  4