Answer:
3/10
Step-by-step explanation:
lets say A, B are the white shirts, and XYZ are the black shirts.
we can make a tree graph, like this to find out how many work.
A B
/ I \ / I \
X Y Z X Y Z
now we know 6 work but we need to find out how many in total there are so we do 5 x 4 since there are 5 shirts available but after you pick theres only 4 left. now we know 6 out of 20 work so we simplify to get 3/10
