Those kids who wrote to Jack are now writing to Jimmy, and what we'd like to have are the answers. Queries Randolph P, anxiously: ""Were you ever a boy scout? . . . I hope you weren't a boy scout because then I won't have to be one too."" Ponders Martin K: ""I wrote you last month to tell you we are poor and need help. I am writing to you again because nothing has happened and we are still poor."" Asks no-nonsense Cynthia N: ""Would you like a fresh tomato? . . . Please tell me if you really like fresh tomatoes because I don't want to waste them."" Bless you Cynthia, Martin, Randolph. Between the plugs for Disneyland and country, the class exercises, the malapropisms and gaffes, kids do sometimes say the truest darn things. With the latest White House addition, quips Bobby W. Amy ""has the First Tree House in the land!