Explanation:
janine is running 10 kilometer per 60 minutes
means janine runs 1 km in
=60/10
=6
since,Janine runs 1 km per 6 minutes
how much time does janine takes to run 15 km
=15 ×6
=90
Therefore Janine takes 90 minutes to run 15 km ie1 hour 30 minutes