Solve the system of linear equations by substitution. 2x - y = -4
2x - 2y = -10

Solve the system of linear equations by substitution.
y = 2x
y = 3x - 3

Solve the system of linear equations by substitution.
2x + y = 5
y = x - 5

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.