The probability of it not being a Katy Perry song is 30/47.
To find this, you find the denominator (bottom number) by adding up all the songs she has total. This will give you 47 as the denominator.
Then you subtract 17 (number if Katy Perry songs) from 47 (total) to get the numerator of the fraction (top). Thus giving you a fraction of 30/47.
I hope this helps!
