A sag curve and crest curve connect a -3.5% tangent section of highway (to the west) with a +2.5% tangent section of highway (to the east). The +2.5% tangent section is at a higher elevation than the -3.5% tangent section. The two tangent sections are separated by 1150 ft of horizontal distance. If the design speed of the curves is 50 mph, (a) what is the common grade between the sage and crest curves (G2 of the sag and G1 of crest, from west to east), and (b) what is the elevation difference between the PVC, and PVTc?