To find the average percentage change in price

How to find percent of change: 
divide the amount of change by the original amount

                                  amount of change
percent of change =
                                   original amount

To find the amount of change just subtract the higher amount by the lower amount. 

For example: What is the percent of change from 40 to 52?

Step 1: Find the amount of change
52-40=12

Step 2: Find the percent of change
12/40=0.3

Step 3: Convert the decimal to a percentage
0.3=30%

The percent of change from 40 to 52 is a 30% increase.