The first sentence reads: "In a perfectly competitive, firm can sell any quantity at the going market price."

One wonders, in a perfectly competitive what?

[NEAS: perfectly competitive market; a typo.]

Some subject verb agreement errors--

On page 5:

1) "If marginal cost change.."
2) "In addition, if marginal cost increase..."

On page 6:

"If marginal cost increase..."

If the profit from operating is less than the variable costs, the firm will shut down.

This should read revenue, not profit.

[NEAS: Correct.]

Ken