Let's use the formula to find the perimeter of a rectangle. 2l+2w=120 We know that the length is twice its width; the equation would be:L=2w We can plug that in to the formula. 2(2w)+2w=120 4w+2w=120 6w=120 120÷6=20=w Since the length is twice its width, 20×2=40. The length is 40 cm. The width is 20 cm. Tell me if this helps!!