ANSWER :
139 feet
EXPLANATION :
The surveyor is 150 feet away from the base of the pole.
The transit is 4 feet tall and the angle of elevation to the top of the pole is 42 degrees.
The illustration will be :
We have a right triangle with an angle of 42 degrees.
The side opposite to the angle is x and the side adjacent to the angle is 150
Using Tangent function :

The height of the pole is x + 4
That will be 135 + 4 = 139 ft