In a library, there are books arranged in a peculiar way. Each book has a title that is a number, and the sum of the numbers of the first three books is 30, while the sum of the last three books is 42. If the number of the middle book is 20, what number should the last book be for the sums to balance?
Category: Brain Teasers · Difficulty: expert
Hint: Think about the relationship between the numbers.
Answer
22
Explanation
If the first three books add up to 30 and the middle book is 20, the last book must be 22 to balance the total of the last three at 42.
This is a expert brain teasers riddle — one of the harder riddles here. The answer is 22.
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