Answer:
Read below :)
Explanation:
So, you have 80 peeps total, right? let's separate them into their core numbers
80 peeps
19 have Crocs
3 have neither
4 have both
61 people with no crocs. of them, 4 have flip flops as well. 80 -3 = 77 so forget the 80 from now on, let's work with 77.
The MIDDLE of the Penn Diagram, where they intersect, 4 people have both.
On the LEFT, 58 people have flip flops, and on the RIGHT, 23 people have Crocs.