Statically Determinate Frame

For the frame shown below, assume all members are AISC W$18$x$50.$ P$1=20$ kN$,$ P$2=40kN$ and $P3=20kN.$ The length parameter a is $2m.$

Part $1.$a: By hand calculation, solve the reaction forces, and develop the shear force and moment diagram for the frame. $(20\%)$

Part $1.$b: Solve part $1.$a using SAP $2000$ for the reaction forces, and the shear force and moment diagram. $(15\%)$

Part $1.$c: Change the frame member section to W $18x40,$ and use SAP $2000$ to re$-$solve the reaction forces, and the shear force and moment diagram. $(10\%)$

Part $1.$d: Compare results from $2.$a$,2.$b and $2.$c$,$ and comment on possible difference. $(10\%)$