What is average fixed cost , average variable cost ,average cost and marginal cost??

Which of the following statements accurately describes how costs and benefits are calculated?

Luc do purchased stocks for $6,000. he paid $4,000 in cash and borrowed $2,000 from the brokerage firm. he bought 100 shares at $60.00 per share ($6,000 total). the loan has an annual interest rate of 8 percent. six months later, luc do sold the stock for $65 per share. he paid a commission of $120 and repaid the loan. his net profit was how much? pls

What is the relationship between marginal external cost, marginal social cost, and marginal private cost? a. marginal social cost equals marginal private cost plus marginal external cost. b. marginal private cost plus marginal social cost equals marginal external cost. c. marginal social cost plus marginal external cost equals marginal private cost. d. marginal external cost equals marginal private cost minus marginal social cost. marginal external cost a. is expressed in dollars, so it is not an opportunity cost b. is an opportunity cost borne by someone other than the producer c. is equal to two times the marginal private cost d. is a convenient economics concept that is not real