[SOLVED] Total cost of box as a function of x?

Hi,

I just started taking a Pre-Calculus math course in College. I took this course years ago and since then have forgotten most of what I have learned. I have come across the following question which I am stuck on.

*A box with a square base has a volume of 600 cubic cm. If the material for the 4 sides and the top costs 5 cents per square cm and the material for the reinforced base costs 10 cents per square cm, express the total cost C of material (in cents) as a function of x, where x is the length of a side of the square base. Write the function in simplified form.*

I have gotten this far:

Area =

Area =

The answer that is given to me is

I can see that if I multiply the 2400 by 5 I will get the but I don't understand where the comes from.

Re: Total cost of box as a function of x?

You need to multiply the parts through by 5 or 10 depending on their worth.

Re: Total cost of box as a function of x?

since the cost of top and base are different so you have to multiply top area with 5 and base area with 10 as

Re: Total cost of box as a function of x?

Thank you very much guys! Now it is clear to me (Clapping) Most impressive how quickly that was answered!