P and Q together can do a job in 6 days. Q and R can finish the same job in 60/ 7 days. P Started the work and worked for 3 days. Q and R continued for 6 days to, finish the work. Then the difference of days in which R and P can complete the job alone is:

Explanation:

(Q+R) 6 days work

= 7×6=42 Units

then in 3 days = total work = 18

P Completes = 60−42=18 units .

P’s eff. 18\3 = 6 units/day

Q’s eff= 10−6=4 units/day

R’s eff = 7−4=3 units/day

P completes whole work in =60\6 = 10 days

R completes whole work in =60\3= 20 days

diff , is20−10=10 days