yx=46;
y=23x
From
6A1ˉa1L1=PaL(L2−a2)
6A1ˉa1L1=∫60(ydx)(x)9(92−x2)=∫60(23xdx)(x)9(92−x2)
6A1ˉa1L1=227∫60x2(81−x2)dx=316.8 kN⋅m3
M1L1+2M2(L1+L2)+M3L2+6A1ˉa1L1+6A2ˉb2L2=0
0+2Mwall(9+0)+0+316.8+0=0
18Mwall=−316.8
Mwall=−17.6 kN⋅m answer
Mwall=ΣMto the left of wall
−17.6=9R−12(6)(4)[3+13(6)]
R=4.711 kN answer
Check using area-moment method
EItA/B=0
(AreaAB)⋅ˉXA=0
13(3)(18)[6+34]+14(3)(3)[6+45(3)]+12(9)(9R)[23(9)]−14(9)(81)[45(9)]=0
148.5+18.9+243R−1312.2=0
243R=1050.3
R=4.711 kN okay