GIVEN:
total length of the banner = 30 ft.
perimeter of the banner = 96 ft.
total width of the rectangle = ?
Let,
the perimeter be "p"
the length be "L"
the width be "w"
We know,
Perimeter (P) of a rectangle = 2 (L + w)
Substituting the values of P, L and w , we get,
96 = 2 (30 + w)
96 / 2 = 30 + w
48 = 30 + w
48 - 30 = w
18 = w
So, the width of the rectangular banner is 18 ft.