Abox is to be constructed with a rectangular base and a height of h cm. the length, l, of the box is 10 cm, and the width, w, is twice the height. which quadratic equation best models the volume of the box?

There are several information's already given in the question. based on those information's, the answer can be easily determined.
Height of the box = h cm
Length of the box = 10 cm
Width of the box = 2h
Then
Volume of the box = Length * height * width
                              = 10 * h * 2h cubic cm
                              = 20h^2 cm^3
I hope that the above procedure is clear enough for you to understand and it has actually come to your desired help.