The tangent of the angle relates the opposite side (height above the window) to the adjacent side (distance between buildings) in the right triangle that models this geometry.
Tan = Opposite/Adjacent
tan(35°) = (height above window)/(distance between buildings)
height above window = (52 ft)tan(35°) ≈ 36.4 ft
Added to the window height of 20 ft, the height of the other building is ...
So to travel 8 3/4 miles, we need 3 1/2 gallons of gas. All we need to do is divide the gallons of gas by miles. So we would do 8 3/4 divided by 3 1/2. 3 1/2 goes into 8 3/4 2 1/2 times.