Question

A and B together can finish a piece of workin 12 days if a alone can finish the same work in 20 days in how many days B alone can finish it

Answer 1

A and B can finish the work in 12 days

⇒ 1 day = 1/12 of the work

A can finish the work in 20 days

⇒ 1 day = 1/20 of the work

Calculate the amount of work B can do in a day:

1 day = 1/12 - 1/20 = 1/30

Find the number of days B needed to complete the work:

1/30 of the work = 1 day

30/30 of the work = 1 x 30 = 30 days

Answer: B will need 30 days if he worked alone.

Answer 2

$\huge {\bold {Solutions :-}}$

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Q: A and B together can finish a piece of workin 12 days if a alone can finish the same work in 20 days in how many days B alone can finish it ?
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A and B do a work in 12 days

(A and B) 's one day work = 1/12

A alone do a work in 20

A' s one day work = 1/20


Now,

B' s one day work =

(1/12) - (1/20)
= (5 - 3)/60
= 2/60
= 1/30


Hence,

$\bold {\underline {B~alone~can~finish~it~in~30~days}}$