We want to find the constant of proportionality for a proportional relationship, we will find that the constant of proportionality is 6.
A general proportional relationship is written as:
y = k*x
Where k is the constant of proportionality.
Here, we have the table:
x y
20 120
18 108
12 72
5 30
Replacing these pairs in the general proportional relationship we can find the value of the constant, for example for the first pair we have:
30 = k*5
30/5 = k = 6
For the second pair we have:
72 = k*12
72/12 = k = 6
That is enough to prove that the constant of proportionality is equal to 6.
If you want to learn more about proportional relationships, you can read:
https://brainly.com/question/12242745
