Answer:
Since this is a proportional relationship,
We know that the number which are proportional are a multiple of each other
the number which we can multiply one of the numbers to get the other number is the constant of proportionality
we could check for proportionality by using the following formula:
p1 / s1 = p2/s2 = p3/s3 = p4/s4 if they were equal, we can say that the relation is proportional
The value of any of the above values, p1/s1 , p2/s2 , p3/s3 , p4/s4 is the constant of proportionality
Therefore, the constant of proportionality = 20 / 5 = 4