$($a$)$ Three forces act at points F$1=,$ F$2=++$ k$,$ F$3=$ k r$1=+,$ r$2=+2$k$,$ r$3=+2+3$k$,[10$ marks$]$ respectively. $($i$)$ Find an equivalent system of forces consisting of a single force acting at the origin together with a couple. $[4$ marks$]($ii$)$ Find the equivalent wrench system consisting of a single force and couple with parallel torque, as well as the wrench pitch.