Physics question: Calculating work done by a motor.?

Im stuck on a question about work done by a motor. A robotic delivery cart carries a part with a mass of 5.4kg a horizontal distance of 12 meters on a flat floor. The wheels have a diameter of 20cm and the drive motor applies a torque of 5 Newton-meters to the wheels while the cart is moving. I need to find out how much work the motor will do, and how much work is done by the gravitational force. How would I calculate these?