Answer: 122 ft
Explanation:
Hi, since the situation forms a right triangle (see attachment) we have to apply the next trigonometric function.
Tan α = opposite side / adjacent side
Where α is the angle of depression, the opposite side is the height of the window above the ground, and the adjacent side (x) is the distance between the neighbor's fence and the house.
Replacing with the values given:
Tan 7 = 15/x
x = 15/tan 7
x = 122 ft
Feel free to ask for more if needed or if you did not understand something.