Can somebody help me with this math question, all you have to do is answer the equation, then it's described, and then it draw it out I'll give you 100 points and a Brainliest

Jeffery conducted a survey in his school and found that 30 of the 50 eighth grade students' favorite subject is mathematics. based on the results, jeffery concluded that out of the 200 students in his school, 120 students' favorite subject is mathematics. select the statement that is true about jeffery's conclusion. a. jeffery's conclusion is not valid because the sample was biased since only 200 students were surveyed. b. jeffery's conclusion is valid because the sample was random since all of the students were eighth grade students. c. jeffery's conclusion is valid because the sample was random. d. jeffery's conclusion is not valid because the sample was biased since all of the students were eighth grade students.

Points a, b, and c form a triangle. complete the statements to prove that the sum of the interior angles of triangle abc is 180

Tan198=asin164=? how to solve this? ?