1. **Problem Statement:** Find the sum of the moments of the given forces about point C in the rectangle ABCD with dimensions AB = 8 cm and AD = 6 cm. 2. **Understanding Moments:** The moment of a force about a point is given by the formula: $$\text{Moment} = \text{Force} \times \text{Perpendicular distance from the point to the line of action of the force}$$ 3. **Given Forces:** Forces are 120 N·cm, 125 N·cm, 317 N·cm, and 312 N·cm. These are moments already calculated or forces with their moment arms. 4. **Sum of Moments:** Since the problem asks for the sum of the moments about point C, we add all the moments considering their directions (assuming all moments are in the same rotational direction or given as positive): $$\text{Sum of moments} = 120 + 125 + 317 + 312$$ 5. **Calculation:** $$120 + 125 = 245$$ $$245 + 317 = 562$$ $$562 + 312 = 874$$ 6. **Final Answer:** The sum of the moments about point C is: $$\boxed{874 \text{ N·cm}}$$