【单选题】If two trains are 120 miles apart and are traveling toward each other at a constant rate of 30 mph and 40 mph, respectively, how far apart will they be exactly 1 hour before they meet?
【简答题】Breanna drove 720 miles to visit some friends. She averaged 60 miles per hour onthe trip out. Coming back, she wanted her drive to be two hours shorter. Howmany miles per hour faster must she drive on...