この問題は過去問からです。答えはあいにく持っておりません。 A bus trip of 450 miles would have taken 1 hour less if the average spees S for the trip had been greater 5 miles per hour. What was the average speed S, in miles per hour, for the trip? (a)10 (b)40 (c)45 (d)50 (e)55
