Write an equation in the Point$-$Slope form that represents the relationship across the $6-$meter roadway surface. The finished grade elevations are $y=100\mathrm{.}500$ and $y=99\mathrm{.}000$ meters along the left and right edges of pavement respectively, as shown in Figure A$\mathrm{.}2.$ Assume $x=0$ at the left edge of pavement.