rectangular prism is a 3D structure with 4 lengths 4 widths 4 heights
Since the question asks about the perimeter, lengths and widths, it is not clear what the 30 feet measure, which is given in the question, refers to! Without that information, it is impossible to answer the question.
You can't find the widths of a rectangle with the lengths because the widths can be anything lower than the lengths. Like if your rectangle had a length of 7 the width can be 6, 5, 4, 3, 2, and so on.
You can get them in various widths and lengths.
stay the same
Different pools have different proportions.
Batt insulation comes in a variety of widths, lengths and thicknesses.
Widths and lengths are two entirely different things. They don't go into anything other than Length x Width = Area.
depends on size of pool, and whether you swim lengths or widths
This can vary, between many lengths and widths and heights and perimeters of the leaf.