we know that the perimeter is the distance around an object. This is also 2 times the length + 2 times the width. We know the width would be X and the length would be 40 feet longer so it is x+40. Now we have 2 (X) + 2 (x+40)=284
Doing the distributive property you would get 2x + 2x + 80=284
add like terms to get 4x+80=284
subtract 80 from both sides to get 4x=204
divide both sides by 4 to get x=51
Width is 51 and width is 40 more than that so length is 91