I want to ask a math problem of senior one: water 15 seedlings. Xiaohong said she watered eight trees, Xiaoli said we were six, and Xiaoming said she would return them.
Six people each watered one tree, six trees were watered and nine trees were not watered. Xiaohong said that eight trees had been watered, which means that two people watered two trees and four people didn't water the second tree. So after watering the 1 tree, the four people who watered the 1 tree began to water the remaining seven trees, so three trees were not watered. Understand?