P can do a work in the same time in which Q and R together can do it. If P and Q work together, the work can be completed in 10 days. R alone needs 60 days to complete the same work. then Q alone can do it in Choose one:
A) 20
B) 24
C) 25
D) 27
E) 30
Work done by P and Q in 1 day = 1/10   Work done by R in 1 day = 1/60   Work done by P, Q and R in 1 day = 1/10 + 1/60 = 7/60   But Work done by P in 1 day = Work done by Q and R in 1 day . Hence the above equation can be written as Work done by P in 1 day Ã— 2 = 7/60   =&gt; Work done by P in 1 day = 7/120   =&gt; Work done by Q and R in 1 day = 7/120   Hence work done by Q in 1 day = 7/120 â€“ 1/60 = 1/24   So Q alone can do the work in 24 days   Answer is 24.
<result>B</result>
P can do a work in the same time in which Q and R together can do it. If P and Q work together, the work can be completed in 10 days. R alone needs 60 days to complete the same work. then Q alone can do it in