15.Working alone,R can complete a certain kind of job in 9 hours.R and S,working together at their respective rates,can complete one of these jobs in 6 hours.In how many hours can S,working alone,complete one of these jobs?(A) 18(B) 12(C) 9(D) 6(E) 3
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![15.Working alone,R can complete a certain kind of job in 9 hours.R and S,working together at their respective rates,can complete one of these jobs in 6 hours.In how many hours can S,working alone,complete one of these jobs?(A) 18(B) 12(C) 9(D) 6(E) 3](/uploads/image/z/12952263-39-3.jpg?t=15.Working+alone%2CR+can+complete+a+certain+kind+of+job+in+9+hours.R+and+S%2Cworking+together+at+their+respective+rates%2Ccan+complete+one+of+these+jobs+in+6+hours.In+how+many+hours+can+S%2Cworking+alone%2Ccomplete+one+of+these+jobs%3F%28A%29+18%28B%29+12%28C%29+9%28D%29+6%28E%29+3)
15.Working alone,R can complete a certain kind of job in 9 hours.R and S,working together at their respective rates,can complete one of these jobs in 6 hours.In how many hours can S,working alone,complete one of these jobs?(A) 18(B) 12(C) 9(D) 6(E) 3
15.Working alone,R can complete a certain kind of job in 9 hours.R and S,working together at their respective rates,can complete one of these jobs in 6 hours.In how many hours can S,working alone,complete one of these jobs?
(A) 18(B) 12(C) 9
(D) 6(E) 3
15.Working alone,R can complete a certain kind of job in 9 hours.R and S,working together at their respective rates,can complete one of these jobs in 6 hours.In how many hours can S,working alone,complete one of these jobs?(A) 18(B) 12(C) 9(D) 6(E) 3
R完成工作用9个小时,R与S共同完成需要6小时,问S需要多少小时?那么1/(1/9+1/S)=6,解得S=18