B) 45

C) 40

D) 30

A and B together can complete the work in 15 days, so (A+B)’s one day work = 1/15

If A alone can complete a work in 20 days then A’s one day work =1/20

Let B alone can complete the work in x days , so B’s one day work = 1/x

Now ,

(A+B)’s one day work = A’s one day work + B’s one day work

=> 1/15=1/20+1/x

=> 1/x= 1/15 – 1/20

=> 1/x = 1/60

=> x=60

Hence B alone can complete the work in 60 days

**Related MCQs:**

- If A and B together can complete a job in 15 days and B alone can complete it in 20 days. In how many days can A alone complete job:
- Asghar can do a job in 60 days and both Asghar and Babar can do the same job in 20 days working together. Babar alone can do the same job in:
- If A and B together can complete a piece of work in 15 days and B alone in 20 days, in how many days can A alone complete the work?
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