First step is to figure out what you know. Which person has the known value of books? Bob. Great -- we'll start with him.
Now, who has something with relation to Bob? Charlie (I'm assuming that you made a typo). Since Charlie has 2/3 books as many as Bob, we need to find 2/3 of 27. There are two ways to do this, but if you're not using a calculator, the way I prefer is to divide by 3, then multiply by 2. What is 27/3? 9. What's 9*2? 18. That means that 18 is 2/3 of 27, and it is also the amount of books Charlie has. The last person we have to find the amount of books for is Jim. Jim has 3 times the amount of books Charlie has. What's 18*3? 54. Your answer is Jim has 54 books. =D
