The first equation of System 2 is the first equation of System 1.
The second equation has an x-coefficient of (A-L). The coefficients of x in System 1 are A and L, so (A-L) is their difference. The second equation of System 2 is the difference of the equations in System 1.
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This is described by Choice D:
The second equation in System 2 is the difference of the equations in System 1. The first equation in System 2 is the first equation in System 1.
