The total monthly operating costs of Chili To Go are:

$10,000 + $0.40X
X = Servings of chili

Determine the average cost per serving at each of the following monthly volumes: 100; 1,000

and basic mathematics doesn't cut it, eh? was it you flunked algebra? X is a multiplication sign, "X" is also an algerbraic value, so 100 is X, and 1000 is X, so you do the rest.

Perhaps you were confused by the order of operations in this equation, admittedly the brackets are assumed.
there are fixed costs and there are variable costs and an incrediable level of stupidy on the part of the person who formulated the question in this manner

If you hope to pass accountancy examinations I suggest you do a mathematics tutorial and a typing tutorial