5. Three girlfriends went to the Olympiad. One of them was in a red dress, another in a yellow one, and the third in a blue one. Their notebooks were of the same colors. It is known that only Svetlana had the same color for her dress and notebook. Neither Tanya's dress nor her notebook were red, and Irina had a yellow notebook. Determine the color of the dress and notebook of each girl.
5. Since Tanya did not have the red notebook, and Irina had the yellow one (also not the red one), the red notebook could only belong to Svetlana. Given that Svetlana has the red notebook and Irina has the yellow one, Tanya must have the blue notebook. Svetlana was in a red dress because the color of her dress and notebook match. The color of Tanya's and Irina's dresses can only be yellow or blue. Thus, we get two solutions: the first - Svetlana in a red dress and with a red notebook, Irina in a blue dress and with a yellow notebook, Tanya in a yellow dress and with a blue notebook; the second - Svetlana in a red dress and with a red notebook, Irina in a yellow dress and with a yellow notebook, Tanya in a blue dress and with a blue notebook. The second solution does not satisfy the condition that only Svetlana's dress and notebook colors matched.

Answer: Svetlana in a red dress and with a red notebook, Irina in a blue dress and with a yellow notebook, Tanya in a yellow dress and with a blue notebook.