1. how many posibilities to divide 10 identical white balls and 10 identical black balls to five different boxes
2.how many posibilities to divide 10 identical white balls and 10 identical black balls to five different boxes that every box have at least 1 ball
3.how many posibilities to divide 10 identical white balls and 10 mixed color different balls to five different boxes
please help me solve it, and please give details in the solution way