This diagram has a heading ‘Doing’. Underneath, the word ‘number’ is written, followed by an arrow pointing to a box. The box contains the operation ‘add 5’. From the box, a further arrow points to a second box which contains the operation ‘multiply by 3’. From the second box, a further arrow points to a third box which contains the operation ‘subtract 4’. From this box, an arrow points to the answer 17. Under the first diagram there is a heading ‘Undoing’. The number 17 is followed by an arrow which points to a box. The box contains the operation ‘add 4’. The output from this operation is 17 + 4 =21 and a further arrow with the answer 21 above it points to a second box. This box contains the operation ‘divide by 3’. The output from this operation is 21 divided by 3 = 7 and a further arrow with the answer 7 above it points to a third box. This box contains the operation ‘subtract 5’ and a further arrow points to the answer 2 (since 7 – 5 = 2).