Maddie wore the green T-shirt.

• She did not order the macchiato because the person with the orange T-shirt did
• She did order the espresso, as we are told
• She did not order the latte because the person with the red T-shirt did
• She did not order the cappuccino, because Carmen did

So we can conclude that she ordered the tea.

Dean wore the blue T-shirt.

• He did not order tea, Maddie did
• He did not order a cappuccino, Carmen did
• He did not order the latte, the person with the red T-shirt did
• He did not order the macchiato; the person with the orange shirt did

Thus, by elimination, he ordered the espresso.

The shirt color for Dennis was not directly revealed.

• He did not order the macchiato (as we are told)
• He did not order tea (Maddie did)
• He did not order cappuccino (Carmen did)
• He did not order espresso (Dean did)

Therefore, he ordered the latte.

Filling in the blanks:

• The macchiato is left for Holly
• We are told that the person who wore the red T-shirt ordered the latte. And, that person is Dennis
• The person who wore the orange T-shirt ordered the macchiato. That person, as we now know, is Holly.
• This leaves the black T-shirt for Carmen, as the only color left.

Here’s the breakdown:

• Dennis: Red T-shirt, ordered latte
• Holly: Orange T-shirt, ordered macchiato
• Dean: Blue T-shirt, ordered espresso
• Carmen: Black T-shirt, ordered cappuccino
• Maddie: Green T-shirt, ordered tea