A computer base unit of mass 7.5 kg is dragged along a smooth desk. If the normal contact force is 23N and the tension in the arm of the person dragging it acts at 23 degrees to the horizontal, then what is the total tension in the person's arms? ... ?

If there isn't any force then the normal contact force will be

N=m*g=7.5*9.81=73.58N

which is 73.58-23=50.58N less

so, there the person must pull at 23 degree upward

break down the tension in two components, vertical and horizontal.

vertical tension = 50.58=T*sin23

T=50.58/sin23=129.45N