Question
Mary and Justin have a bicycle race. Mary cycles at a speed of 18 km/h. Justin cycles at a speed of 21 km/h. If Justin lets Mary start 30 min before him, how long will Justin take to catch up with Mary?
3 m

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Mary and Justin have a bicycle race. Mary cycles at a speed of 18 km/h. Justin cycles at a speed of 21 km/h. If Justin lets Mary start 30 min before him, how long will Justin take to catch up with Mary?