$(15$ Points$)$ A $1600-$ft$-$long sag vertical curve $($equal tangent$)$ has a PVC at station $120+00$

and elevation $1500ft.$ The initial grade is $-3\mathrm{.}5\%$ and the final grade is $+6\mathrm{.}5\%.$ Determine the

elevation and stationing of the low point, PVI, and PVT$.$