Mr. Mason’s class is going on a field trip. There are 27 students. There will be 1 adult for every 9 students. Mr. Mason wants to know how many adults (n) are needed for the field trip. Which of the following equations should he use?
A. 9n + 27
B. 27 – 9n
C. 9n = 27 - 1
D. 9n = 27