Chain Rule - General QuestionsChain Rule - Important Formulas and Facts Directly Proportional:If two amounts are said to be in directly proportional then, as one amount increases another amount increases at the same extent. e.g. Your earnings is directly proportional to your working hours. Work more hours, get more pay; (direct proportion). Inversely Proportional:when one amount decreases at the same extent that the other increases. e.g Speed and travel time are Inversely Proportional As speed increases, travel time decreases And as speed decreases, travel time increases Note: To solve problems by chain rule, you should compare every item with the term to be found out.