Answer:
It should be the last one
Explanation:
Area is 6000 yd2
LW = 6000
field must be 40 yards longer than its width
L = W + 40
Replace L with W+40 in 1st equation to solve for Width
(W+40)(W) = 6000
W2 + 40W - 6000 = 0
This is a quadratic but is factorable
Factors of -6000 that add to 40 are (100)(-60)
(W+100)(W-60) = 0
W = -100 or W = 60
Since the width will not be negative discard -100
The width is 60 yards
Length is W+40 = 100 yards
I know this isn't your problem, but I helped a friend do something similar so I just used that example to help you understand what you have to do for your problem. Hopefully this will help you