What is a favor Jamie asks Landon to do for her?

In Chapter 4 of A Walk To Remember Landon's feelings for Jamie are all mixed-up. He accepts the fact that Jamie is a good person, even though she's not very popular at school. After all, she did step in and save him from Lew at the dance, and she didn't have to do that. Despite Jamie's caring, compassionate nature, Landon figures that if he really liked her he would've asked her out again. But as he hasn't, then according to his own unique logic, he mustn't really like her.
In any case, Landon's spared the necessity of asking Jamie out because she calls him and asks if they can meet up. Landon reluctantly agrees and he and Jamie sit outside Reverend Sullivan's house. (As the reverend doesn't allow his daughter to be alone in the house with a young man). During their chat, Jamie asks Landon for a favor. She asks him if he'd be willing to audition for the part of Tom Thornton in the school's production of The Christmas Angel. Jamie wants the performance to go off without a hitch for her father's sake. But the problem is that Eddie Jones, who's currently scheduled to play Tom Thornton, has a pronounced stammer. Hence Jamie's request that Landon steps into the breach. Landon reluctantly agrees, and in doing so, shows that whatever he might say to himself, deep down he really does like Jamie.