It would be best if you draw or sketch the system described above. You will see that a right triangle would be formed where the height of the triangle is equal to the height of the tower and the base would be equal to the shadow casted by the tower. We can use a trigonometric function for this.
tan (angle) = height / base
angle = tan^-1 (height /base )
angle = tan^-1 (154 /166 )
angle = 42.85 degrees