What page of The Outsiders says that Cherry was the greasers' spy?

Dally tells Johnny and Pony that Cherry was a spy for the greasers because she gave them information.

Dally, Johnny, and Pony met Cherry at the movies.  Even though she was a Soc, they talked to her.  Cherry did not like Dally, and Johnny got him to leave.  Johnny and Pony spent time with Cherry and her friend Marcia. 

Johnny and Pony were not aware that Cherry had talked to Dally.

“…Two-Bit's a good fighter....

Dally tells Johnny and Pony that Cherry was a spy for the greasers because she gave them information.

Dally, Johnny, and Pony met Cherry at the movies.  Even though she was a Soc, they talked to her.  Cherry did not like Dally, and Johnny got him to leave.  Johnny and Pony spent time with Cherry and her friend Marcia. 

Johnny and Pony were not aware that Cherry had talked to Dally.

“…Two-Bit's a good fighter. Hey, I didn't tell you we got us a spy."

"A spy?" Johnny looked up from his banana split. "Who?"

'That good-lookin' broad I tried to pick up that night you killed the Soc. The redhead, Cherry what's-her-name." (Ch. 5)

The relationship between Cherry and the gang is a complicated one.  She became friends with Pony and Johnny, but when her boyfriend Bob saw them together he got upset.  She got in the car with him because she did not want a fight.  However, later that night Pony and Johnny were in the park when Bob and his friends jumped them.  Bob was drowning Ponyboy when Johnny killed Bob to save Pony.

Cherry was sad when her boyfriend died, but she also understood that he was a mean drunk.  She loved Bob, but was tired of the violence between greasers.  Dally explained that Cherry was in danger just talking to the greasers.

"She came over to the vacant lot the night Two-Bit was jumped. Shepard and some of his outfit and us were hanging around there when she drives up in her little ol' Sting Ray. That took a lot of nerve. Some of us was for jumping her then and there, her bein' the dead kid's girl and all, but Two-Bit stopped us. …” (Ch. 6)

Dally tells them that Cherry feels like the whole thing is her fault, including the rumble, because she was seen with Johnny and Pony that night.  She wants the fighting to end and is trying to prevent the rumble. 

Pony realizes that when trying to help them, Cherry is not being a Soc.  She is being a “dreamer.”  Cherry had told Pony that things are rough all over, meaning that Socs have problems too.  She liked Pony because he was deep.  Pony realized that they both saw the same sunset.