An equal-tangent sag equal tangent vertical curve is designed for 45 mi/h. The low point is 237 ft from the PVC at station 112 + 37 and the final offset at the PVT is 19.355 ft. If the PVC is at station 110 + 00, what is the elevation difference between the PVT and a point on the curve at station 111 + 00?