or
or
A=1/30 ; B=1/15=2/30; C=1/10=3/30;
B and C help only on every 2nd and 3rd days. So that in a week alone work on 1st, 4th, 5th, 6th, and 7th day.
So that days need to finish the work is = 1 + (1+2+3) + 1 + (1+2+3) + 1 + 1 + 1 + 1 + (1+2+3) + 1 + (1+2+3) = 11 days ad 100 percent of work.
Here, (1+2+3) is that work when they work together
