x = width. the perimeter of a rectangle is 2*length + 2*width, so the perimeter of this rectangle is 2x + 2(5x) = 72. distribute the two to get 2x + 10x = 72. so 12x = 72. divide by twelve to get x = 6. the width is six, so the perimeter (5x) is 30. the area of a rectangle is length times width, 30*6, so the area is 180 m.
