In raymond's run which detail supports the prediction that squeaky will not let gretchen win the race

In "Raymond's Run," Squeaky decides to coach her mentally handicapped brother Raymond in track. Squeaky attends the May Day celebration, where she wins an important race. During the race, she sees Raymond running alongside the track. This is when she decides to be his coach.

Hazel Elizabeth Deborah Parker ("Squeaky") has proven herself to be a skilled runner. She has a wall of trophies and ribbons and wins every race she runs.
At the May Day celebration, Squeaky and her rival Gretchen face off in a big race. While running, Squeaky sees Raymond running alongside the track and realizes that he could be a runner, too.

Squeaky wins the race, but by the time she hears the announcement she has already decided to put her own running career on the back burner to coach Raymond.