Let the length and width of the rectangle be L and W.

The perimeter of a rectangle is 7 times its width.

=> 2L + 2W = 7W

=> 2L = 5W

=> L = (5/2)W

Area = 40

=> L*W = 40

=> (5/2)W*W = 40

=> W^2 = 16

=> W = 4

L = 10

**The length of the rectangle is 10 and width is 4**