Final answer:
To eliminate the y-variable, you must multiply the second equation by the same factor as the first equation, which is 2.
Step-by-step explanation:
To eliminate the y-variable in the system of equations, you need to multiply the second equation by the same factor as the first equation.
Since the first equation is multiplied by 2, you must multiply the second equation by the same factor, which is also 2. So the answer is 2 (B).