# Tonya said the percent increase from 25 to 40 is 37.5%. Describe Tonya's error and give the correct percent increase?

Nov 21, 2016

The absolute increase is $40 - 25 = 15$

#### Explanation:

The error is that this was taken as a percentage of the new situation:
15/40xx100%=37.5%

But increase (or decrease) is always taken from the old situation:
15/25xx100%=60%

The rule is:
Increase/decrease% =("New"-"Old")/("Old")xx100%

Where a negative outcome means a decrease.