Pls help with all of them

Solve the system. -a+4b+2c=-8 3a+b-4c=9 b=-1 a.(0,11) ,-1,2) c.(1,1,-2) d.(2,-1,-1)

2people are trying different phones to see which one has the better talk time. chatlong has an average of 18 hours with a standard deviation of 2 hours and talk-a-lot has an average of 20 hours with a standard deviation of 3. the two people who tested their phones both got 20 hours of use on their phones. for the z-scores i got 1 for the chatlong company and 0 for talk-a-lot. what is the percentile for each z-score?

Zroms according to the synthetic division below, which of the following statements are true? check all that apply. 352 -2 6 -12 12 2 4 0 i a. (x-3) is a factor of 2x2 - 2x - 12. b. the number 3 is a root of f(x) = 2x2 - 2x - 12. c. (2x2 - 2x - 12) = (x + 3) = (2x + 4) d. (2x2 - 2x-12) - (x-3) = (2x + 4) e. (x+3) is a factor of 2x2 - 2x - 12. o f. the number -3 is a root of fx) = 2x2 - 2x - 12. previous