9.5.3 Changing Formulas
The same technique can be used to change formulas. For example, earlier in the unit, you found a formula to convert dollars into euros:
However, what if you were from Europe and wished to convert euros into dollars, say while you were shopping on vacation?
Then you would need a formula for the number of dollars based on the number of euros. We can tackle this by drawing the “doing and undoing” diagrams for this situation:
So, starting at the right of the undoing diagram, the formula for converting euros into dollars is:
Activity: Miles and Kilometers
To change kilometers into miles, you used the formula:
Starting with “distance in kilometers,” draw a doing diagram to get the distance in miles. Draw the undoing diagram and write down the formula for changing miles into kilometers.
Your formula should start “distance in kilometers =.”