In a race from point X to poinY and back, Jack averages 30 miles per hour to poi
hour back to point X. Sandy averages 20 miles per hour in both directions. Between Jack and Sandy, who finish first?请帮忙翻译,并给出答案,谢谢! 选择题,A. Jack B. Sandy C They tie D. Neither 是同时吗?为何?没想通?