Marginal product. Helpp i dont know how to do thiss?

The answer is 150 packets per month. Marginal product of labor is the amount of extra products you can produce by hiring 1 more worker. If after hiring the third helper demand increased even more and she were to hire a forth worker, output could increase to say 800 packets. Now the marginal product of labor for the 4th worker would be 200 packets per month. Get it?