David and Amrita had an equal number of marbles. After Amrita gave 50 marbles to David, he had 5 times as any marbles as her. find the total number of marbles they had?
Here's My Answer by Zach (Singapore)
Step 1: For this question, it will be easier to start from the "After" model and work backwards to the "Before" model. We first draw 5 boxes to represent the number of marbles David had and 1 box to represent the number of marbles Amrita had after the transfer of 50 marbles.