1) The area of the rectangular field is 2c^3 - c^2 + 6
2) The length is c - 2
3) Divide the area by the length to obtain the width:
2c^3 - c^2 + 6 | c - 2
-----------------------
-2c^3 + 4c^2 2c^2 + 3c + 6
------------------
3c^2 + 6
-3c^2 + 6c
-------------------------
6c + 6
-6c + 12
-------------
18
Given that the division is not exact (the residue is 18) you cannot determine an exact width.
So, I guess ther is a mistake in some of the given expressions. Just use the right expressions and use this procedure to get the answer.