It should be multiplied by the opposite of the coefficient of y in the first equation, hence
B)) -2
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Actually, it depends on your choice of next step. Multiplying by -2 lets you add the two equations. Multiplying by 2 means you need to subtract one equation from the other. We usually find addition easier, so we would usually choose -2, but either can work. It depends on whether you like to add negative numbers or subtract positive ones.
