Please help and explain provide examples

2-A manager in your organization tells you over coffee one morning, "Differential costing is easy; variable costs are the only costs that are relevant." As the organization's accountant, how would you respond to this statement?

Later in your conversation this same manager opens a folder and produces a document he just received regarding a special order at a price that he believes is "below cost." The manager is opposed to accepting orders of this nature because he feels every sale needs to carry a fair share of full costs in order to keep the company from failing.

What would be your reply to this manager?