A ladder whose length $L$ is $12$ m and whise mass $m$ is $45$ kg rests against a wall. Its upper end is at a distance $h$ of $9\mathrm{.}3$ m above the ground. The c$.$m$.$ of the ladder is $\frac{1}{3}$ of the way up the ladder. A firefighter whose mass $M$ is $72$ kg climbs halfway up the ladder. Assume that the wall, but not the ground, is frictionless. What forces are exerted on the the ladder by the wall and by the ground?