Curtis threw 15 darts at a dartboard. 40% of his darts hit the bull's-eye. how many darts did not hit the bull's-eye?

Curtis threw 15 darts at a dartboard. 40% of his darts hit the bull's-eye.
Let’s find out how many darts did not hit the bull's-eye.
=> 15 darts = 100%
=> 40% of 15 hits bull’s eye.
Now let’s solve:
=> 40% / 100% = .40
we need to get the 40% value of 15 to know how many darts was able to hit bull’s eye.
=> 15 * .40 = 6 darts
Thus, out of 15, 6 of the darts hit bull’s eye,.

If i'm correct the answer is $15.97