This isn't a difficult question, nor does it require calculations. But I still just don't get the answer.
How many people are directors of both Company K and Company R?
 There were 17 directors present at a joint meeting of the directors of Company K and Company R, and no directors were absent.
 Company K has 12 directors and Company R has 8 directors.
I would think the answer is A. "...17 directors present at...meeting of the directors of Company K and Company R...none were absent."
But the answer is C.
Maybe I haven't had enough food today.
I think where you got confused was the difference between 'How many people are directors of both
Company K and Company R' and 'How many total directors are there
in Company K and Company R'. The question asks how many people are directors of both companies.
There are some people who are directors of only Company K, some who are directors of only company R and some who are directors of both. Now think, is statement 1 sufficient? It only tells us the total number of directors, not the ones common to K and R.
If statement 2 alone sufficient. It again tells us how many each company has, not how many they have in common.
When you take both statements together, you find out that total there are 17 directors. Company K has 12 and company R has 8 which adds up to 20 so 3 directors must be common to them. Now we get the information we were looking for. Answer (C).
Check out sets theory for more such questions.
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