The length of the pen is 8 meters and the width is 5 meters.
Explanation:
Since it is a rectangular goat pen the length and width can the the same number. So now just think of all the number that can be multiplied to get 40 and try them to see if they fit the perimeter too.
Say you get 8 and 5.
To check this you have to multiply the length times the width to see if it works for the area (which is 40 meters.
And 8 × 5 = 40, so these side lengths satisfy the area part... now to check if it works for the perimeter.
To find perimeter you add up all the sides. So if the length and width were to be 8 and 5 you would have to add up 8 + 8 + 5 + 5 To get the perimeter.
The total of 8 + 8 + 5 + 5 = 26 which satisfys the perimeter measurement.
So now you know the side lengths 8 (L) and 5 (W) work!
