Question

The question is in the image below.

Answer 1

The answer is __

because of __

Explanation:

Answer 2

The fourth:

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.

Ax + By - (Lx + My) = Ax + By - Lx - My = (A - L)x + (B - M)y