MathDB

In Miss Lies' class there are only students who never lie and students who always lie. All students know which category they belong to. During the day in a class discussion, every student in the class says about every other student or he or she a liar or not. In total, it is said

320

times that someone is not lying. The next day, one of the students who always lies is sick. There will be one again organize such a class discussion in which no mention is made of the sick pupil. Now it is said

300

times that someone does lie. How many liars are there in the Miss Lies' class ?

Problem Statement