Shapovavov A.B.
10 children were standing in a row. The total number of nuts that the girls and boys had was equal. Each child gave one nut to each of the children standing to their right. After this, the girls had 25 more nuts than they originally had. How many girls are in the row?
The first child from the left gave away 9 nuts, which means he had 9 fewer nuts; the second child gave away 8 nuts and received 1, which means he had 7 fewer nuts. Continuing with similar reasoning, we notice that the first five children had 9, 7, 5, 3, and 1 fewer nuts, respectively, while the next five had 1, 3, 5, 7, and 9 more nuts, respectively. Since \(1+3+5+7+9=25\), the girls could only have been the last five children.

## Answer

5 girls.