Which solution method, graphing, substitution, or elimination, is the most appropriate for solving each each system of equations? Explain. Will mark brainlist!!!

1st Question

3x + 8y = -4

2x - 4y = 16

2nd Question

6x - y = 16

x = 4y - 5

3rd Question

x + y = 19

3x - 2y = -3

(b) suppose that consolidated power decides to use a level of significance of α = .05, and suppose a random sample of 100 temperature readings is obtained. if the sample mean of the 100 temperature readings is x⎯⎯ = 60.990, test h0 versus ha and determine whether the power plant should be shut down and the cooling system repaired. perform the hypothesis test by using a critical value and a p-value. assume σ = 5. (round your z to 2 decimal places and p-value to 4 decimal places.)