Question

The circulation of a newsletter decreased from 3,200 to 2,464. What was the percent of decrease in circulation?

Answer 1

it's 23%

Answer 2

If you write it as rate equivalences you got something like:
\[100/3200=x/2464\]
solving x you can find:
\[x=(100 * 2464)/3200\]
\[x=77\]
We've found that only 77% of newsletters are in circulation, the percent of decrease is:
\[100-77=23\]

Answer 3

just for explaining, I'm not refutating your good answer