First, let's create an equation for this problem. Let x represent the percent decrease.

=

Next, cross multiply.
39.50x = 450
Now, all you would need to do is isolate the x. To do this, you would divide both sides of the equal sign by 39.50.
x =
11.3924050633
Remember to round the answer to the nearest tenth.
11.3924050633 ≈ 11.40%
The percent decrease is 11.40%.
I hope this helps!