Amanufacturer of shipping boxes has a box shaped like a cube the side length is (5a+4b) what is the volume of the box in terms of a and b show work

For a regular cube:
side length =

This problem has a lot of distributing. I suggest you use a grid to make sure each term is distributed (see attached image on how to do this)

For our problem:
side length =
(use FOIL)

Multiplying 5a(25a²+40ab+16b²) =
Multiplying 4b(25a²+40ab+16b²) =
Combine like terms. (200a²b + 100a²b = 300a²b, 80ab² + 160ab² = 240ab²)

volume = s³ = 

The slope of the function is 0.5.