Answer: 0.8
Step-by-step explanation:
Assuming that the data is arranged in the table I have attached, the following will apply.
To find the constant of proportionality, we can use k = y/x. Here, our y-value is the sale price and our x-value is the original price. We will substitute the given values and divide.
k = y/x = 20/25 = 0.8
The constant of proportionality is 0.8.
