A and B can together finish a work in 30 days. They worked at it for 20 days and then B let. The remaining work was done by A alone in 20 more days. B alone can do the entire work in
option
(a) 48 days
(b) 50 days
(c) 54 days
(d) 60 days

• A+B 's 1 day work = 1/30
  A+B's 20 days work = 20*1/30 = 2/3
  Remaining work left = 1-2/3 = 1/3
  A does 1/3 work in ---> 20 days
  A does 1 work in ---> x days
  x = 3*20 = 60 days
  
  A ll take 60 days to complete the whole work
  A's 1 day work = 1/60
  Therefore B's 1 day work = (A+B)'s 1 day work - A's 1 day work
  => 1/30 - 1/60
  =1/60
  So B's 1 day work = 1/60
  B ll complete the entire work alone in 60 days
  
  Ans : 60 days
• 10 years agoHelpfull: Yes(26) No(0)
• ans 60 days
  A & B together do work in 30 days
  they together work for 20 days and they finish 2/3 of toal work in 20 days
  now A alone do the remaining (1-2/3) in 20 days
  so he takes 60 days to do the total work
  now a&b's one day work=1/30
  and a's one day work=1/60
  so 1/60+1/x=1/30
  x=60 days
• 10 years agoHelpfull: Yes(9) No(0)
• In one day A+B will do 1/30 work
  in 20 days 2/3 work will be finished. so the remaining work is 1/3.
  So,1/3 work is completed by A in 20 days that means a can do 1/60 work in 1 day.
  Now, 1/60 + B = 1/30 => 1/60
  i.e 1/60 is the work B alone can do in 1 day. So to finish all the work by B he will take 60 days to finish the work.
• 10 years agoHelpfull: Yes(2) No(0)
• let, total work = Lcm(30,20)= 60 then A+B=30 days then 1 day work of them is (60/30)= 2
  A+B work for 20 days so the total workdone is 20*2= 40 so the remaining work is 60-40= 20
  remaining work done by A alone so then A's 1 day work is 20/20= 1
  then A complete the whole work in (60/1) day= 60 days
• 9 years agoHelpfull: Yes(1) No(0)
• let total work is 100%
  then A+B complete 100/30=3.33%/day
  hence in 20 days they complete 20*3.33=66.6% of work
  remaining work is =100%-66.6%=33.4%
  remaining work is done by A in 20 days
  hence A alone will work 1.67% /day
  hence B's 1 day work =3.33%-1.67%=1.66*60=100(approx)
  
• 9 years agoHelpfull: Yes(0) No(4)
• LET THE total work be w
  given that A&B can does work in 30 days together
  so in 1 day the had done 1/30 part of the work
  so for working for 20 days they both together had completed they both had completed 2/3rd of the work so,
  remaining work=1/3
  which is done by A in 20 days
  so a does 1/3rd of the work in 20 days
  so A can complete work 1/60 of the work in 1 day so
  A completed 2/3 of the work in 40 days
  nd A also does 1/3 of the work together with B so b does 1/3 of the work in 20 days so total days taken by the B is 20*3 =60 days
• 8 years agoHelpfull: Yes(0) No(0)