So, Juan is 3rd, and Tami has at least 2 ppl in front of her, she can't be third because Juan is, so she's fourth. Kari is not 1st, leaving the only space to be 2nd from Kari.
David can read 50 pages in 50 minutes. (50 pages)/(50 minutes) = 1 page/minute Since David reads 1 page per minute, in 80 minutes David can read 80 pages.