"How are the Americans?"
It would also be correct, accordingly with the text here (see Swahili Greetings):
Watoto hawajambo? - How are the children?
Je, watoto hawajambo? - How are the children?
Watoto hawajambo. - The children are fine.
Please note that the jambo greeting and the response to the jambo greeting allows for the word order to be reversed. Therefore, the example above can be posed as:
Hawajambo watoto? - How are the children?
Hawajambo watoto. - The children are fine.
Swahili Grammar for Introductory and Intermediate Levels: Sarufi ya ... https://books.google.com.ar/books?isbn=0761863826