A system of equations is given below: y = 3x + 4
2x + 3y = 10

Which of the following steps could be used to solve by substitution?

3x + 4 = 2x + 3y
2x + 3(3x + 4) = 10
2(3x + 4) + 3y = 10
3(y = 3x + 4)

Twenty-five percent of the customers entering a grocery store between 5 p.m. and 7 p.m. use an express checkout. consider five randomly selected customers, and let x denote the number among the five who use the express checkout.

Answer this question, only if you know the answer. 30 points and brainliest!

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.