Dont understand how to solve​

49xy +34y - 72z. determine the degree of the polynomial

For which of the following counts would a binomial probability model not be reasonable? a)the number of people in a classroom born in januaryb) the number of people in a classroom with red hair c) the number of people admitted to a hospital in a day with a particular disease d) the number of heart beats in a one-minute perio.

How is this equation completed? i cannot find any examples in the book.