WDYM BY SUBSTITUTION when u get the two proportions, u say "substitute" im giving 100

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.

Angle mno is s rotated 180 degrees counterclockwise about the origin to form angle m’n’o’. which statement shows the measure of angle m’n’o’?

What function has a range {yly< 5}? question on picture above^