While using a pencil sharpener, a student applies the forces and couple shown. 

(a) Determine the forces exerted at B and C knowing that these forces and the couple are equivalent to a force-couple system at A consisting of the force R= (3.9 lb)i+ R_yj − (1.1 lb)k and the couple MR/A = M_xi +(1.5 lb f ⋅ t) j − (1.1 lb f ⋅ t) k. .

(b) Find the corresponding values of R_y and M_x.