I will give brainiest

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.

Percent increase and decrease. original number: 45 new number: 18

At the movie theatre, child admission is $5.20 and adult admission is $9.70. on sunday three time as many adult tickets as child tickets were sold, for a total sales of $788.90. how many child tickets were sold that day?