Y by
The set of 18 numbers is given

Here the sign
indicates the color red and the sign
indicates the color blue.
Prove that no matter how we choose 10 elements from the set, there are always two of different colors with a sum of 10.

Here the sign


Prove that no matter how we choose 10 elements from the set, there are always two of different colors with a sum of 10.
This post has been edited 3 times. Last edited by cip1703, Oct 2, 2024, 2:35 PM
Reason: correction
Reason: correction