if d vectors c,a=xi+yj+zk& b=j r such that a, c,b form a rt handed system den c={ans zi-xk}

 a force 39kg wt is acting at a point P(-4,2,5) in d direction (12,-4,-3) d moment of dis force about a line thru d origin having d direction of (2,-2,1) is [ans -76 units]