For the beam and loading shown, determine:

$($a$)$ the reaction forces at points A and $B($upward is positive$),$ and

$($b$)$ the bending moment at $x=0\mathrm{.}1L$ from point $A.$

$RA=,P$

$RB=,P$

$M(x=0\mathrm{.}1L)=PL$