Let x by the length and y be the width
Area = x y
x y = 6000
Since the length must be 40 yards longer than the width
x = y + 40
Substituting x to the area
(y +40) y = 6000
y^2 +40y - 6000 = 0
This is quadratic equation. Using the quadratic formula we get the positive value of y,
y = 60
So,
x = y + 40 = 60 + 40 = 100
The length is 100 yards and the width is 60 yards.
