Question 673927
Percent change is (new - old)/old or (n - o)/o.  Think of it as noo!
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From 40 to 60...
40 is "old"
60 is "new"
So (60 - 40)/40 = 20/40 = 1/2 or 50% change.
Just be sure to always parenthesize the numerator or you will always accidentally subtract 1 from the new number.