Answer:
It will take Molly 1 hour to catch up to Jonas.
Step-by-step explanation:
Since Molly starts riding her bike to school 20 minutes after her brother Jonas does, and Molly pedals 12 miles per hour, and Jonas pedals 9 miles per hour, to determine how much time will it take for Molly to catch up to Jonas the following calculation has to be done:
Jonas = 9 miles per 60 minutes = 3 miles per 20 minutes
Molly = 12 miles for 60 minutes
Jonas = 3 miles + 9 = 12
Molly = 12
Therefore, it will take Molly 1 hour to catch up to Jonas.