Question

solve no 20...............

Answer 1

According to question,
A and B can do a work in 12 days
∴ (A + B)’s one day’s work = 1 /12
Similarly, (B + C)’s one day’s work = 1/15
and (C + A)’s one day’s work = 1/20
On adding all three,

∴ 2 (A + B + C)’s one day’s work = 1/12+ 1/15 + 1/20
= 1/5
and (A + B + C)’s one day’s work = 1/10
∴ A, B and C together can complete the work in 10 days.