To determine the relationship between the number of patients cleaned (denote as \( p \)) and the number of hours worked (denote as \( h \)), we start by establishing the rate of cleaning based on the information given.
From the problem statement, we know:
- The hygienist cleans the teeth of 5 patients by noon, and she takes a lunch break at that time.
- The average rate is 9 patients in 4 hours.
First, we can find the rate of cleaning:
\[ \text{Rate} = \frac{\text{Patients}}{\text{Hours}} = \frac{9 \text{ patients}}{4 \text{ hours}} = 2.25 \text{ patients per hour} \]
Now, if \( h \) represents the number of hours worked after lunch, the number of patients she sees after lunch can be given by:
\[ p = 2.25h \]
This equation captures the number of patients \( p \) in terms of the hours \( h \) that the hygienist works after lunch.