Answer:
40
Step-by-step explanation:
Let's use the Rule of Three Simple to answer the question this way:
Stock price Percentage
$ 15 100%
$ 9 x
15 * x = 9 * 100
15x = 900
x = 900/15
x = 60
Percentage decreased = 100 - 60
Percentage decreased = 40
The company's stock decreased 40 percent