Answer:
Step-by-step explanation:
In system B, the first equation is the same, so clearly the <em>second</em> equation has been replaced. The only other equation in the system is the <em>first</em>, so that is the one that is multiplied by some number.
The number it is multiplied by must make the y coefficient be the opposite of the y-coefficient in the second equation, so they cancel when added. That is, the multiplier times -1 must be -4, so the multiplier must be <em>4</em>.
The purpose of doing this is to ensure the solution of System B <em>is exactly</em> the same as that of System A.
