1. Gear kinematics. An input shaft drives Gear 1 with 20 teeth at 1800 rpm which mates with the 80-tooth Gear 2 which in on the intermediate shaft. Also on the intermediate shaft is Gear 3with 18 teeth. It mates with Gear 4 on the output shaft, where Gear 4 has 90 teeth. How fast does Gear 2 spin, in rpm? Gears 2 and 3 spin at the same speed, so what is the speed of Gear 4? What is the ratio of the input speed to the output speed? Is this compounded train "reverted?"