Final answer:
The exact distance from Green Gables to Bright River is not provided in the given texts, and one would need to consult L.M. Montgomery's "Anne of Green Gables" for the specific mileage.
Step-by-step explanation:
The distance from Green Gables to Bright River is not specifically provided in the given texts. However, we can infer from the various passages that distances in the protagonists' journeys often span several miles. For instance, one excerpt mentions a ride of over sixty miles, potentially seventy, and another describes a journey of seventy or eighty miles via a canoe. While these distances do not directly answer the student's question, they reflect that travel distances in the referenced literature could be significant. To determine the precise mileage from Green Gables to Bright River, one would need to refer back to the original text of "Anne of Green Gables" by L.M. Montgomery, where the setting of Green Gables is actually stated.