Answer:
6x - 11 feet
Explanation:
Dale is standing (2x + 7) feet height from the base of the tower. 
And the tower is given to be (8x - 4)feet tall. 
We have to find the distance between Dale and the top of the tower. 
Now, the distance between dale and the top of the tower = height of the tower - height of Dale = (8x - 4) - (2x + 7) = (6x - 11) feet. (Answer)