$4-124,4-125$ The forces and couple moments exerted on the toe and heel plates of a

snow ski are $F_t=\{-50i+80j-158k\}N,M_t=\{-6i+4j+2k\}N*m,$ and $F_h=$

$\{-20i+60j-250k\}N,M_h=\{-20i+8j+3k\}N*m,$ respectively.

$($a$)$ Replace this system by an equivalent force and couple moment acting at point $O.$

Express the results in Cartesian vector form.

$($b$)$ Replace this system by an equivalent force and couple moment acting at point $P.$

Express the results in Cartesian vector form.