In the graph, the constant of proportionality is 40
<h3>Calculating the constant of proportionality</h3>
From the question, we are to determine the constant of proportionality
The constant of proportionality = 
From the graph, a point on the line is (1, 40)
That is,
When x = 1 and y = 40
Thus,
The constant of proportionality = 
Constant of proportionality = 40
Hence, the constant of proportionality is 40
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5×21/-1+9
105/-1 +9
-105 +9
-96
hope that helps
Answer:
The best estimate for the average rate of change is 
Step-by-step explanation:
we know that
the average rate of change using the graph is equal to
In this problem we have
Substitute
Perimeter = 18 miles
Perimeter = 2a + 2b
2a + 2b = 18
a = ?
b = 7
18 = 2a + 2*7
18 = 2a + 14
2a = 18 - 14
2a = 4
a = 2
Area = a * b
Area = 2 * 7 = 14 miles2