Three people are fighting over a book. The mass of the book is m=9.18kg. Each person exerts a force on the book, F. The angle between the first person and the second person's force is 125.9 degrees. If the first person is pulling with a magnitude of F1=233.9 N of force and the second force is exerting a force of F2=2212.9N, what is the magnitude of the force (in newtons) exerted by the third student if the book does not accelerate?