Question 1076885
Lets consider the triangle legs as X and Y

For bigger triangle 
x1 = 35
y1 = ?

For smaller triangle
x2 = 4
y2 = 12

By using similar solids:
[(X1)/(Y1)] = [(X2)/(Y2)] 

[(35)/(Y1)] = [(4)/(12)] 

Simplify,

Y1 = 105 ft