why does brother leon ask archie to help sell the chocolates?

Archie wonders why Brother Leon is talking to him about the chocolate sale in such a manner. The teacher muses that, while the boys at Trinity are middle-class, their families are not wealthy enough to permit a raise in the tuition. All this is meant to impress upon Archie that the chocolate sale must be a huge success. Archie is to use his influence in The Vigils to compel the boys to sell all the chocolates. While the words are never spoken by Brother Leon directly, Leon knows that Archie has influence in the secret group that rules the school. Archie pushes back, but Leon levels his gaze at him and Archie remembers that Leon could ruin his grade in algebra. Archie leaves saying that The Vigils will help.