This diagram has a heading “Doing.” Underneath, the phrase “distance in km” is written, followed by an arrow pointing to a box. The box contains the operation “multiply by 0.6214.” From the box, a further arrow points to the phrase “distance in miles.” Under the first diagram there is a heading “Undoing.” The phrase “distance in miles” is followed by an arrow which points to a box. The box contains the operation “divide by 0.6214.” From the box a further arrow points to the phrase “distance in km.”

9.5.3 Changing Formulas