Why do you think Ponyboy has an easier time coping with Dally's death than he does with Johnny's? How does the note make Johnny's death easier for Ponyboy to accept?

Ponyboy was closer to Johnny as well as he is the reason that Johnny died. The note makes it easier because he knew that in his final moments Johnny thought of him and told him basically to remember the good times with him. And knowing that Johnny would've wanted him to be happy made his death easier to accept.