How Do You Write an Expression for the Cost of Running a Machine?

[mathdad]

The cost of running a machine is partly constant and partly varies as the number of parts machined. Write an expression to show the cost?

My Reasoning:

Let C = cost

Let x = partly constant

Let y = partly varies

Let k = constant of proportionality

C = x + yk

Right?

 

[Joppy]

I would have thought "partly constant and partly varies" means one part varies, and one part is constant.. Since a varying constant is.. well, a variable? I'm not sure though. The wording is strange with this one.

 

[MarkFL]

Let's let $F$ be the fixed costs and $M$ be the marginal cost (the cost to machine one part), and $x$ be the number of parts machined. Then the total cost $C$ would be given by:

$$C(x)=Mx+F$$

 

[mathdad]

Let's let $F$ be the fixed costs and $M$ be the marginal cost (the cost to machine one part), and $x$ be the number of parts machined. Then the total cost $C$ would be given by:

$$C(x)=Mx+F$$

We used different variables but correct nonetheless.