Anna and Becker both participate in a bicycle race. Anna pedals 20 mph and Becker pedals at 18 mph. Anna crosses the finish line 10 minutes before Becker. How long is the race?
Their differnce in speed is 2 mph
1/6 hr * 18 m/hr = 3 miles to go when Anna finishes
Anna gets ahead 2 miles every hour 3 miles /2m/hr = 1.5 hr for anna to finish 1.5 hr x 20 m/hr = 30 mile bike race