The reason is because she didn't survey the school, but only surveyed her class, and to add to that It didn't say it was a random selection of students. Juliet concludes that short stories is the favorite type of book of the students in her school because 80% of the students in her class like short stories. Just because most of her class chose short stories she believes the rest of the school will have the same choice.
Angle UTV is basically given: it's 138°.
Moreover, since UTV is isosceles, the other two angles have the same measure x. We thus have

So, TUV is 21°, and VUW is complementary, so it must be 69° so that they sum up to 90°
23,356 the answer rounded to nearest whole number