27 of the 97 students in Henry's grade have a pet. What is the ratio of the number of students who have a pet to the number of students who do not have a pet?
Write your answer as a fraction. Use a slash ( / ) to separate the numerator and denominator.
The number of students who have a pet is 27, and the number of students who do not have a pet is 97 - 27 = <<97-27=70>>70.
The ratio of the number of students who have a pet to the number of students who do not have a pet is 27/70. Answer: \boxed{27/70}.