P can do a work in 48 days. Q can do the same work in 9 days and R can do the same in 12 days. Q and R start the work and leave after 3 days. P finishes the remaining work in --- days. Choose one: A) 7 B) 8 C) 9 D) 10 E) 20
Work done by P in 1 day = 1/24   Work done by Q in 1 day = 1/9   Work done by R in 1 day = 1/12   Work done by Q and R in 1 day = 1/9 + 1/12 = 7/36   Work done by Q and R in 3 days = 3Ã—7/36 = 7/12   Remaining work = 1 â€“ 7/12 = 5/12   Number of days in which P can finish the remaining work = (5/12) / (1/48)= 
<gadget id="calculator">(5/12) / (1/48)</gadget>
<output>20</output>
20   Option 20
<result>E</result>
P can do a work in 48 days. Q can do the same work in 9 days and R can do the same in 12 days. Q and R start the work and leave after 3 days. P finishes the remaining work in --- days.