Determine the horizontal distance between two points A and $B$ whose elevations above datum are $h_A=1980ft$ and $h_B=1425ft$ and whose images a and $b$ on a vertical photograph have photo coordinates $x_a=2\mathrm{.}95in.,y_a=2\mathrm{.}32$ in$.,x_b=-1\mathrm{.}64$ in$.,$ and $y_b=-2\mathrm{.}66$ in$.$ The cam le flying height above datum $7500$ fT$.$