Answer:
Let w be the width. Length is then w+5.
(w+5)w=300
w²+5w=300
w²+5w-300=0
w=-2.5+√306.25 I ignore the other zero since w must be positive.
w+5= 2.5+√306.25
The field is 2.5+√306.25 meters long by -2.5+√306.25 meters wide
i think that's the answer