Answer:
First you want to find the unit rate of each girl. But before doing that, you must convert one hour to minutes. There is 60 minutes in one hour. So
Addison runs 2 kilometers in 20 minutes, while Emma runs 5 kilometers in 60 minutes. We need to divide minutes by kilometers to find out how long it takes for them to run one kilometer.
Thus...
Addison:
20 divide 2 is 10. So Addison takes 10 minutes to run one mile.
Emma:
60 divided by 5 is 12. So Emma takes 12 minutes to run one mile.
Since the track coach wants to pick the fastest girl, Addison shall be the right option.
Have a good day!~