The most common diagram observed for this question is similar to that drawn by Rozie. The diagram expresses clearly the relationship between the red box and the blue box. A concrete representation of the problem is given in the diagram drawn by Hogan. He drew th balances the first with the pointer at 3, the second has the pointer at 1 and the third has the pointer at 4. He then successfully wrote down the step 36/4. Izyan's diagram shows a line, marked out with 36 parts to represent the total weight 36kg. He counted along the line and marked a longer division on 9 and said that the weight of the blue box is 9kg. He then proceeded to calculate the weight of the red box as 36-9.