The area (A) of a rectangular polygon is the product of the width (W) and the length (L). That is,
A = L x W
It is said in the problem that the width of the rectangle is the greatest common factor of 15n³ and 20n⁷ which is 5n³. We calculate for the length of the rectangle by dividing the given area by the width.
Length = (15n³ + 20n⁷)/(5n³)
Length = 3 + 4n⁴
