A rectangular storage container with an open top is to have a volume of 10 m³. The length
of the base of the container is twice its width. Assume that the width of the base of the
container is x metres and the height of the container is y metres. Assume that material for
the base of the container costs $15 per square metre, while material for a side costs $20
per square metre.
(a) Find an equation to express the volume of the container in terms of the variables
and y, and then write y in terms of x.
(b) Find an equation for the surface area of the container (bottom + 4 sides), using only
the variable x.
(c) Find an equation for the cost of the container, using only the variable x.
