Answer:
D. 9n = 27
Explanation:
If we need one adult for every 9 students, we can represent that as 9n:
if n is the number of adults.
Because we have 27 students, the equation 9n = 27 works.
A better way of formatting the equation is:
n = 27/9
Because it directly shows what the number of adults is, but with some reformatting, it is clearly the same equation.