This would vary on the perspective of the solver. In this case, the solution would be
A A A B B B B C C C
A A A B B B B C C C
A A A B B B B C C C
A A A B B B B C C C
A A A B B B B C C C
A A A B B B B C C C
A A A B B B B C C C
A A A B B B B C C C
A A A B B B B C C C
A A A B B B B C C C
such that Employee A would constitute 30%, Employee B would constitute 40% and Employee C would constitute 30% of the work.
I hope I was able to answer your question. Have a good day.