To find
To divide 20 miles by 5 hours, what conversion should be made to make the calculation correct?
Step-by-step explanation
20 miles refer to the distance travelled
5 hours refers to the time taken
So dividing distance by time would give us speed
Since both are different physicals quantity so their units need not be same.
Conclusion
The correct statement is
Divide the two numbers as given--units do not have to be the same when dividing.