This shows a figure containing a doing and undoing diagram. The doing diagram has two rectangular boxes in the middle, the 1st containing ‘add 4’ linked to the 2nd box on the right containing ‘multiply by 2’. To the left of the 1st box is the word number, linked by an arrow pointing right. On the right of the 2nd rectangular box is an arrow pointing right to the number 14.

The undoing diagram has two rectangular boxes in the middle, the 1st containing ‘divide by 2’ linked to the 2nd box on the right containing ‘subtract 4’. The arrow linking the two boxes has the number 7 above it. To the left of the 1st box is the number 14, linked by an arrow pointing right. On the right of the 2nd rectangular box is an arrow pointing right to the number 3.

3.1 Doing some doing and undoing