Set theory: find the intersection

[Matt_92]

Homework Statement

In a group of 30 people each person twice read a book from books A, B, C. 23 people read book A, 12 read book B and 23 read book C.

(a) How many people read books A and B?
(b) How many people read books A and C?
(c) How many people read books B and C?

Homework Equations

The Attempt at a Solution

I'm not sure how to start. Any hints will be very much appreciated.
Thank you

 

[verty]

There seem to be errors with this problem. For example, the problem is symmetric in A and C, so parts (a) and (c) are really the same question. And usually people don't read the same book twice but that seems to happen here. I would ignore this problem for being unclear or having errors.

Also, in the current form it looks prohibitively difficult to solve, suggesting that there is a mistake.

 

[berkeman]

Homework Statement

In a group of 30 people each person twice read a book from books A, B, C. 23 people read book A, 12 read book B and 23 read book C.

(a) How many people read books A and B?
(b) How many people read books A and C?
(c) How many people read books B and C?

Homework Equations

The Attempt at a Solution

I'm not sure how to start. Any hints will be very much appreciated.
Thank you

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