I have had to confer with other committee members on this question.
In the first example you have given, the system of equations is not aligned in print. Although the equal signs are aligned, the variable "x" is not aligned in the two equations.
I would left align in cell 3 as you have shown on the solution at the left side of the page.
In the second example, the variables again are not aligned in print (only the equal signs are aligned). This solution is correct as you have shown it.
Because the questions (in both of the examples you have used) say that these are a "system of equations", they must be preceeded and followed by a blank line. Although this is not clearly stated in the code book, the errata for the Nemeth lessons has updated §181 c. (1) Ununified System of Equations to say that "… the arrangement is considered to be spatial and blank lines must be left above and below it."