A rectangular box is to have a square base and a volume of 40
ft3. If the material for the base costs $0.35 per square
foot, the material for the sides costs $0.05 per square foot, and
the material for the top costs $0.15 per square foot, determine the
dimensions of the box that can be constructed at minimum cost.
= Length
Width
Height
how do i find length width and height