Using the slope concept, it is found that he stepped back 63.44 feet.
The slope is given by the vertical change divided by the horizontal change.
It's also the tangent of the angle of depression.
Initially, we have that:
Hence:
[tex]\tan{68^{\circ}} = \frac{85}{d}[/tex]
[tex]d = \frac{85}{\tan{68^{\circ}}}[/tex]
[tex]d = 34.34[/tex]
When he stepped back, the angle was of 41º, hence:
[tex]\tan{41^{\circ}} = \frac{85}{d}[/tex]
[tex]d = \frac{85}{\tan{41^{\circ}}}[/tex]
[tex]d = 97.78[/tex]
97.78 - 34.34 = 63.44.
Hence he stepped back 63.44 feet.
You can learn more about the slope concept at https://brainly.com/question/26291396