John and Max had an equal amount of money each. After john spent $25 and Max spent $18, the ratio of John's money to Max money was 2:3. How much money did each boy have at first?
Here's My Answer by Zach (Singapore)
Step 1: This question involves the Non-Constant Transfer Concept. It is easier to start from the "After" model. Since the ratio of John's money to Max money was 2:3 after the transfer, we draw 2 boxes to represent the amount of money John had and draw 3 boxes to represent the amount of money Max had.