Final answer:
The reason for Mrs. Slade's envy towards Mrs. Ansley cannot be determined from the given references. The answer would require context from the specific literary work that features these characters.
Step-by-step explanation:
The reason Mrs. Slade was envious of Mrs. Ansley is not explicitly provided in the provided reference texts. However, envy is a common theme in literature and can stem from various sources such as wealth, relationships, qualities, and lifestyle. Since none of the exerpts provided directly discuss Mrs. Slade or Mrs. Ansley, we cannot definitively answer which aspect specifically led to the envy of Mrs. Slade towards Mrs. Ansley.
To accurately answer this schoolwork question, it would be necessary to refer to the specific work of literature in which these characters appear. Only with the proper context from the story can we ascertain the precise reason for Mrs. Slade's envy towards Mrs. Ansley.