Algebra practice question

Answer: C. 7

Add the equations to eliminate y: 3x = 12, so x = 4. Then y = 4 − 1 = 3. x + y = 7. Choice B is just x; read what's actually asked.

Why the other answers are wrong

A. 3

3 is the value of y alone; the question asks for x + y, so add x = 4 to it.

B. 5

5 isn't produced by the system — adding the equations gives 3x = 12, so x = 4 and y = 3. Solve for both variables, then add.

D. 9

This comes from flipping the second equation to y − x = 1, which gives y = 5 instead of y = 3; as written, x − y = 1 means y = x − 1 = 3.

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