Okay, let's break this down step-by-step:
1) We need to choose a slope within 6 to 8 feet of vertical change for every 100 feet of horizontal change.
Let's choose a slope of 7 feet of vertical change for every 100 feet of horizontal change.
2) So for every 100 feet horizontally, the zip line will drop 7 feet vertically.
3) We know the ending point height, but we need to calculate the starting point height.
4) If the ending point height is 100 feet above the ground, then for every 100 feet of horizontal distance, the line drops 7 feet.
So to drop 100 feet vertically, the line would have to travel 100 / 7 = 14.29 ~ 15 100-foot segments.
5) So if the ending point is 100 feet above the ground,
the starting point will be 100 + (15 * 7) = 100 + 105 = 205 feet above the ground.
6) Therefore, the difference between the starting and ending point heights is 205 - 100 = 105 feet.
So the difference between the starting and ending point heights of the zip line is 105 feet.
Please let me know if any of the steps are unclear or if you have any other questions! I'm happy to explain further.