2013 ToT Spring Junior A p2, 10 boys and 10 girls in a line
Source:
March 4, 2020
Sumalgebra
Problem Statement
Twenty children, ten boys and ten girls, are standing in a line. Each boy counted the number of children standing to the right of him. Each girl counted the number of children standing to the left of her. Prove that the sums of numbers counted by the boys and the girls are the same.