Example--A blind, online poll. Suppose the question asked is something like "Do you trust left-handed people?" Assume that no left-handed people would say "no".
The poll reports that 10% answered no. But if 15% of those polled are lefties, how would their "yes" votes be filtered out--in order to see what righties think?
It can't be as simple as subtracting them out, because 10 minus 15 is -5. Hopefully this can have a simple answer as I never took any math higher than Alg. 2, and had to take it a few times to pass.