The dimensions are 60 yards by 100 yards
Proof:
Let the wdth be x and the length be x+40
x(x+40)=6000
x²+40x=6000
x²+40x-6000=0
use the quadratic formula
x= -40+ or - √40²-4*1*-6000
x= 60, -100
but distance but be positive so the dimensions are 60 yards by 100 yards
