Question 780223
A can do work in 12 Days,b in 6 days and c in 3 days.A and B start working together and after day,C jons them.The total numbers of days required to complete the work is 
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let x=number of days required to complete the work
A's work rate=1/12
B's work rate=1/6
C's work rate=1/3
{{{x/12+x/6+(x-1)/3=1}}}
LCD:12
x+2x+4x-4=12
7x=16
x=16/7
ans: a)