Help with A, B and C

Problem 2. You have prescribed knee extension exercises for your patient using a cuff weight. The patient performs these exercises sitting on the edge of her chair with her entire thigh supported by the chair and the lower leg off the floor. The weight of the lower leg and foot is 55 N and the cuff weight is 50 N. The cuff weight is located 0.25m from the knee joint center. The weight of the lower leg and foot is 0.11 m from the knee joint center. For each of the following positions, calculate the magnitude of the resistance moment on the knee (note: the grey circle is the knee). (6pts) A. -90 B. -450 C. 0