Question

If 14 out of 20 like chocolate then how many people dislike chocolate?

Answer 1

You know from the given information, there are 20 people in total. 
When asked 14 people stated that they liked chocolate. This leaves a group of people out of 20 who do not like chocolate. 

20-14=6 

You know from this that 6 people do not like chocolate while 14 of them do 

Hope I helped :)