Zina solves a system of linear equations by elimination and finds that the solution to a system is (2, 2). One of the equations is a + b = 4. Which answer could be the other equation?

Substitute the solution (a, b) = (2, 2) into each possible equation. The equation a + 3b = 8 gives 2 + 3(2) = 8, so the solution satisfies it as well as a + b = 4. Choice C is just a multiple of the given equation, so the two equations would not determine a unique solution.

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