Question 309762
A completes one work in 20 days.
 B cmpletes the same work in 25 days 
while C completes the same in 30 days.
:
 If initially A started the work and after 4 days he quits it.
 Next B carry forward the work & he completed the half of the remaining work
 then how in how many days the C will complete the remaining work?
:
Let the completed work = 1
:
A does {{{4/20}}} = {{{1/5}}}; {{{4/5}}} remains
:
B does {{{1/2}}} * {{{4/5}}} = {{{2/5}}} remains
:
{{{C/30}}} = {{{2/5}}}
cross multiply
5C = 60
C = {{{60/5}}}
C = 12 days to complete it
:
:
Check
A does {{{1/5}}}
B does {{{2/5}}}
C does {{{2/5}}} 
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total 1