Hey there! I'm happy to help!
We see that 3195 minus a certain percent of 3195 is equal to 2546. Let's call this percent decrease p and then solve.
3195-3195p=2546
We subtract 3195 from both sides.
-3195p=-649
We divide both sides by -3195.
p≈0.20312989
To convert to a percent, we multiply by 100, giving us about 20.3% decrease.
Have a wonderful day! :D