Astudent is trying to solve the system of two equations given below:
equation p: y + z = 6
equation q: 5y + 9z = 1
which of the following is a possible step used in eliminating the y-term?
(y + z = 6) ⋅ 9
(y + z = 6) ⋅ −5
(5y + 9z = 1) ⋅ 9
(5y + 9z = 1) ⋅ 5

Explain the answer and how to do it

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.

One astronomical unit (1 au) is about 1.496 alt tag missing. kilometers. if you wrote this number of kilometers in regular decimal notation (for example, 528 and 3,459 are written in regular decimal notation), how many zeros would your number have?