建议使用官方纸质指南，查看对照完整题目
【OG20-P167-133题】
Working simultaneously at their respective constant rates, Machines A and B produce 800 nails in x hours.Working alone at its constant rate, Machine A produces 800 nails in y hours. In terms of x and y, how many hours does it take Machine B, working alone at its constant rate, to produce 800 nails?
-
分析A选项
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx -
分析B选项
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx -
分析C选项
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx -
分析D选项
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx -
分析E选项
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
- 网友解析
我有更好的解析 
暂无雷哥网文字解析
预约名师一对一题目解析课程设Machine B的速度为a，则(800/y)*x+ax=800，a=(800（y-x）)/xy，所以Machine B生产800nails需要时间xy/y-x
题目讨论 （3条评论）
-
emily666
这道题我终于可以秒做了
0
0
回复
2020-06-01 16:10:07
-
夜晚半透明
总共
800个 x小时 效率800/x
单独a
800个 y小时 效率800/y
单独b
单独b效率=总共效率-单独a效率=800/x - 800/y
时间=总量/效率
单独b 时间=800/（800/x - 800/y）= e选2
0
回复
2019-05-22 19:49:59
-
emily666回复夜晚半透明
谢谢，解释得很清楚
0
0
回复
2020-03-11 17:37:40
-
-
默默
800/x +800/y= 800* [(x+y)/xy]
0
0
回复
2018-04-21 00:09:52
-
默默回复默默
800*xy/800(x+y)
0
0
回复
2018-04-21 00:11:09
-
默默回复默默
题看错了，是知道联合速度，求单个的，所以选D
0
0
回复
2018-04-21 00:16:42
-
