Algebra practice question

Answer: 5

Infinitely many solutions means the first system's equations are multiples: a = 10/2 = 5. In the second system, 2(4) + 3y = 5 gives y = −1, so b = 4 − (−1) = 5.

Common wrong answers

If you answered 3

3 comes from b = 4 + (−1), adding instead of subtracting.

If you answered 10

10 uses a = 10, forgetting to halve.

If you answered -1

−1 is y, not b.

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