a. After the mod. One wall is “x” longer than original (horizontal in diagram) and the other is “x” shorter (vertical)
(30+x)(30-x)
b. He original area = 30 x 30 = 900 sq. ft.
The mod. Area is (30+6)(30-6) = 36x24= 764 sq. ft.
So the room was largest to begin with when it was a square