Which property does the equation illustrate (x+5)+9=x+(5+9)

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.

Solving systems of linear equations: tables represent two linear functions in a systemöwhat is the solution to this system? 0 (10)0 (1.6)0 18,26)0 18-22)

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.