An internal wheel B with 80 teeth is keyed to shaft F. A fixed internal wheel with 82 teeth is concentric with B. A compound wheel DE gear with two internal wheels, D has 28 teeth and gears with C, while E gears with B. The compound wheel revolves freely on a pin which projects from a disc keyed to a shaft A co-axial with F. If all the wheels have the same pitch and shaft A makes 800 rpm, determine the speed of F.