Sasha noticed that the graph of the sales of yearbooks represented a proportional relationship. How could she have calculated the constant of proportionality by looking at the graph? A. She could divide any y-value by its corresponding x-value.
B. She could divide any x-value by its corresponding y-value.
C. She could add any y-value to its corresponding x-value.
D. She could subtract any x-value from its corresponding y-value.