John and Jay run the 220-yard dash ,and Jay wins the race by 10 yards .if Jay runs the race in 30 seconds ,what is the r
问题描述：
John and Jay run the 220-yard dash ,and Jay wins the race by 10 yards .if Jay runs the race in 30 seconds ,what is the rate of each boy in yards per second?how long would it take John to run the 220-yard dash?
答
题意如下：
John和Jay比赛220码短跑,Jay以10码优势赢得了比赛.如果Jay跑完全程用了30秒,那么每个人的速度是多少?John跑完220码需要多长时间?
解法如下：
对于Jay：220码÷30秒=22/3 码/s
Jay跑完220码时,用了30秒,此时John跑了220-10=210码
因此John的速度是：210÷30=7 码/s
John跑完全程需要：220÷7=220/7 秒