1. The problem statement, all variables and given/known data Emily's brother, Jack, is now 105cm tall, having grown by one sixth of his height a year ago. How tall was Jack one year ago? 2. Relevant equations Now my teacher told me to do this: x = 105 - (105/7) x = 105 - 15 x = 90 cm 3. The attempt at a solution So 90cm is the answer. But can someone explain to me very simply why we divided by 7 the 105 as the question says that Jack grew by one sixth and not by one seventh? Many thanks.