Answer:
Step-by-step explanation:
Percent change is found using the formula ...
percent change = ((new value) - (old value))/(old value) × 100%
This can be divided out to be ...
percent change = ((new value)/(old value) -1) × 100%
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For your numbers, the change is ...
percent change = (8400 -6400)/6400 × 100% = 31.25%