54 POINTS: PLS HELP ASAP !! Solve the following system of equations using the substitution method.

6x + 3y = 15
y = 1 - x

A. (3,-4)
B. (-3,4)
C. (4,-3)
D. (-4,3)

Measure of angles 31 (x+4) (3x+9) me

3.17 scores on stats final. below are final exam scores of 20 introductory statistics students. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 57, 66, 69, 71, 72, 73, 74, 77, 78, 78, 79, 79, 81, 81, 82, 83, 83, 88, 89, 94 (a) the mean score is 77.7 points. with a standard deviation of 8.44 points. use this information to determine if the scores approximately follow the 68-95-99.7% rule. (b) do these data appear to follow a normal distribution? explain your reasoning using the graphs provided below.

If p(a) = 0.70 and p(b) = 0.20, then a and b are independent events if