How does Percy feel when he reads the article about his car accident?

He felt angry and miserable.

Explanation:

In the book, 'The Lightning Thief', we learn of Percy Jackson a young student who just finished Grade 6, and who narrated his ordeal of being half-human. He was sent to a camp known as Camp Half-blood where children who were known to be half-bloods were sent. While there he received a Newspaper article from the New York Times which was kept at a strategic place by someone whom he felt did not like him in the camp.

Seeing his recent picture and that of his mother Sally Jackson angered him and after reading the article he felt miserable. The article explained that their car which was a '78 Camaro was discovered flipped over and that Sally Jackson and her son were not seen at the scene. Percy was a suspect to his mother's disappearance because his step-father reported that he had weird and violent tendencies.      

from the excerpt from the "the dark game" the reader can infer that folke cronholm was spying for the allied nations.