help me choose the correct answers, in question 18, the one i chose might be wrong, thanks a lot.

Question 18 4 pts Given a price of $5.00 per unit, a total of 55 units produced, and a total revenue of $275.00; and, then a 56" unit is produced for a total revenue of $280.00, what is the marginal revenue of the 56th unit? (O Marginal revenue of the 56th unit equals $55.00 (O Marginal revenue of the 56th unit equals $25.00 (O Marginal revenue of the 56th unit equals $15.00 (O Marginal revenue of the 56th unit equals $10.00 @ Marginal revenue of the 56th unit equals $5.00 Question 19 4 pts Given a profit equal to -$200.00 at output quantity equal to O O Total Variable Cost equals $200.00 (O Total Average Variable Cost equals $200.00 (O Total Marginal Cost equals $200.00 O Total Fixed Cost equals $200.00 O Total Average Fixed Cost equals $200.00 Question 20 4 pts Given a total cost of $400.00 at output quantity equal to 10 and total cost of $460.00 at output quantity equal to 11, what it the marginal cost of producing the 11t unit? O $0.00 O $60.00 O $400.00 O $460.00 O $860.00