I saw the image that should have been posted with this word problem.
The rolls of wrapping paper is cylindrical in shape.
Roll A : length = 30 inches ; diameter = 3 inches
Roll B : length = 24 inches ; diameter = unknown
Lateral surface area = 2 π r h
Lateral Surface area of Roll A = Lateral Surface area of Roll B
2 * 3.14 * 1.5in * 30in = 2 * 3.14 * r * 24 in
282.60 in² = 150.72 in * r
282.60 in² / 150.72 in = r
1.875 in = r
diameter is 2 times the radius = 1.875 in * 2 = 3.75 inches
The diameter of Roll B is 3.75 inches.