Answer:
(n - 3)(2) or 2(n - 3)
Explanation:
The area of a rectangle is its length multiplied by its width. But which side is length is up to you; there are 2 choices!
If the side marked n - 3 is the length, then the side marked 2 is the width. the area is (n - 3)(2).
On the other hand, if the side marked 2 is the length, then the side marked n - 3 is the width. The area is 2(n - 3).
By the way, both those expressions are equivalent to 2n - 6.