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Algebra / Systems of two linear equations in two variables Difficulty: Easy

y=-3x

4x+y=15

The solution to the given system of equations is x,y. What is the value of x ?

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Explanation

Choice C is correct. The given system of linear equations can be solved by the substitution method. Substituting -3x for y from the first equation in the given system into the second equation yields 4x+-3x=15, or x=15.

Choice A is incorrect and may result from conceptual or calculation errors.

Choice B is incorrect and may result from conceptual or calculation errors.

Choice D is incorrect. This is the absolute value of y , not the value of x .