318. guys, please help me to solve this problem. many thanks!!
Ps.A,B单独完成完成w工作,A用的时间比B多2小时。如果A,B一起做,需要3小时完成5W/4公司,问A单独作需要多多少时间完成2W工作?
答案是12小时。
同意
举报
suppose A needs x+2 hours, B: x hours , their speed is w/(x+2), w/x
according to 如果A,B一起做,需要3小时完成5W/4公司, (5w/4)/ [w/(x+2)+w/2] =3, then x=4, at last, the A speed is w/6
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