A company is researching the cost to increase the size of a shipping container. The cost of labor to Increase the container can be modeled by the function r(z) = 50 + 10z. where x is in feet. The container has dimensions 2x feet, (5-z) feet, and (5+x) feet. Which of the following statements are true about the function c(x) representing the cost of labor per cubic foot? Select all that apply.