Question

A and B together can complete a piece of work in 12 days, B
and C can do it in 15 days and A and C can do it in 20 days.
A, B and C together can complete it in
(a)
(b) 16 days
(c) 10 days
(d) 8 days
12 days​

Answer 1

Step-by-step explanation:

1/a+1/b=1/12

1/b+1/c=1/15

1/c+1/a=1/20

add all

2(1/a+1/b+1/c)=1/12+1/15+1/20

1/a+1/b+1/c = 5+4+3/60 = 12/60 =1/5

so, they all together can complete the work in 5 days