Question

a, b and c together can do a piece of work in 15 days B alone can do it in 30 days and C alone can do it in 40 days in how many days will a alone do the work ​

Answer 1

Given,

(A+B+C) can do a piece of work in = 15 days

(A+B+C)’s 1 day work = 1/15

B alone can do a piece of work in = 30 days

B’s 1 day work = 1/30

C alone can do a piece of work in = 40 days

C’s 1 day work = 1/40

So,

A’s 1 day work = 1/15 - 1/30 + 1/40

= 1/15 - 4+3/120

1/15 - 7/120

8−7 /120

= 1/120

∴ A can do a piece of work in 120 days.