Question 1033129
The tree is x feet above John's line of sight.
When John is y feet away, the angle of elevation is 35 degrees.
The height of the tree is the opposite side.  The distance from the tree is the adjacent side.
tan 35=x/y
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When he is (y-30) feet from the tree, the angle is now 47 degrees
tan 47=x/(y-30)
x=y tan 35
x=(y-30)tan 47
Therefore,
y tan 35=(y-30)tan 47
ytan35-ytan47=-30tan 47
y(tan35-tan47)=-30 tan 47
-0.3722y=-32.17

y=86.4 feet tall, but we have to add the 6 feet John is tall, so the height is 92.4 feet.