The displacement vector is AB = Ob-OA = (7 7,0)-(20, 15) = (- 13,-15).

The work of F 1 is f1* ab =1* (13)+2 * (15) =-43.

The F2 work is F2 * AB = 4 * (13)-5 * (15) = 23,

Since the resultant force is f 1+F2 = (1, 2)+(4,5) = (5,3),

Therefore, the success rate is (f1+F2) * ab = 5 * (13)-3 * (15) =-20. (The unit of work is Joule)