Final answer:
The missing value of x cannot be 4.
Step-by-step explanation:
To determine which value could not be the missing value of x, we need to analyze the given options. The options are A. -6, B. -2, C. 4, and D. 8.
This question is related to linear equations, so we should consider the linear equations mentioned in the Practice Test. From the options, A. -6 and C. 4 are the values of x in the linear equations y = -3x and y = -9.4 - 2x respectively. Therefore, B. -2 and D. 8 are the remaining options.
Based on the given information, B. -2 and D. 8 are possible values for the missing value of x, so the answer is C. 4 (which is not a possible value for the missing value of x).