in a jar we have 3 balls one red one white one black
3 people choose a ball and return it back.
x represents the number of different colors which the 3 people chose
y represents the number of white balls chosen.
we have in total 27 possibilities
3 people chose 2 different colors(from the existing 3) and non of them was white
so each guy need to chose red or black out of 3 balls
why the answer is