Question

5
A and B do a piece of work in 12 days, B and C in 15 days and A and C in 20
days. In how many days A, B and C together will complete the work.?
(a) 10 days (b) 11days (c) 9 days (d)12 days
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Answer 1

Answer:

10 days

Step-by-step explanation:

a+b 1 day work=1/12 ->eq1

b+c 1 day work=1/15. ->eq2

a+c 1 day work=1/20 ->eq3

adding all 3 eqs

a+b+b+c+a+c=1/12+1/15+1/20

2(a+b+c)=(5+4+3)/60

2(a+b+c)=12/60=1/5

a+b+c=1/(5×2)=1/10

A,B,C can complete the work in 10 days