[Mathematical logic (other)]

In the room, there are 85 balloons - red and blue. It is known that: 1) at least one of the balloons is red, 2) in every arbitrarily chosen pair of balloons, at least one is blue. How many red balloons are in the room?

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Think about whether there can be two red balls in the room.

## Solution

Since among any two balls, one is blue, there cannot be two red balls in the room. Therefore, there are 84 blue balloons and 1 red balloon in the room.