Retracing the steps and undoing each stage helps us solve the missing pieces in between to find that missing information.
When you think about the reasons you might buy an Apple product, the specific features of a smartphone or i Pad might not necessarily come to mind.
Similarly, you probably don’t think about all the products you’ve bought when discussing the benefits of using Amazon.
However, as the bus travels, we know that there are 2 main events which occurred that changes the total number of passengers on the bus each time.
In addition, we are given the total number of passengers in the end.