In the figure here, a red car and a green car move toward each other in adjacent lanes and parallel to an $x$ axis. At time $t=0,$ the red car

is at $x_r=0$ and the green car is at $x_g=218m.$ If the red car has a constant velocity of $24\mathrm{.}0k\frac{m}{h},$ the cars pass each other at $x=43\mathrm{.}7m.$

On the other hand, if the red car has a constant velocity of $48\mathrm{.}0k\frac{m}{h},$ they pass each other at $x=76\mathrm{.}6m.$ What are $($a$)$ the initial

velocity and $($b$)$ the $($constant$)$ acceleration of the green car? Include the signs.