Change in altitude:
42,000 - 18,000 = 24,000 feet
Rate of change = 24,000 feet / 12 minutes = 2,000 feet per minute
Because the plane was going down, the rate of change would be negative.
The rate would be -2,000 feet per minute.
Answer:

Step-by-step explanation:
Rule: 

Considering that each student has only one birthday, each input will be related to only one output, hence this relation is a function.
<h3>When does a relation represent a function?</h3>
A relation represents a function when each value of the input is mapped to only one value of the output.
For this problem, we have that:
- The input is the student's name.
- The output is the student's birthday.
Each student has only one birthday, hence each input will be related to only one output, hence this relation is a function.
More can be learned about relations and functions at brainly.com/question/12463448
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You can find how many he gets for each dog.
For example, let's pretend Juan gets $3 for each dog to walk, then he would've walked 4 dogs. But in this real problem we don't know how much he gets for each dog.
So, you can find the amount of money Juan saved by knowing how much is for each dog walked.