Percent difference? - Math Central

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Question from Cathy:

I am trying to verify a "percent of difference" as stated on a tax form. I cannot seem to come up with the equation to do so.
Here are a few examples on the form:
Last year $62.91 this year $66.05 tax difference $3.14 percent difference -5.64%
Last year $ 2014.97 this year $1982.93 tax difference $-32.04 percent difference 57.56%
Last year $97.66 this year $79.58 tax difference $-18.08 percent difference 32.48%
I have tried several different ways and per some of Q&A's already on your site I still have a problem and would appreciate some assistance.
Thanks-Cathy

Hi Cathy,

Percentages are strange creatures, we are all sloppy in the way we use the term. When we say percentage we should say "percentage of what". I don't have a copy of the US income tax form but from the numbers you sent I can tell you

$3.14 is -5.64 % of -$55.66
-$32.04 is 57.56% of -$55.66
-$18.08 is 32.48% of -$55.66

Does this help?

Harley

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