Algebra practice question

Answer: 38

Solve the system: double the second equation to get 6x − 4y = 12, then add to 5x + 4y = 32 to eliminate y: 11x = 44, so x = 4. Substitute: 3(4) − 2y = 6 gives 2y = 6, y = 3. Then 8x + 2y = 32 + 6 = 38. Compute the requested combination, not just x or y alone.

Common wrong answers

If you answered 3

That's y. The question asks for 8x + 2y, so use x = 4 as well: 32 + 6 = 38.

If you answered 4

That's x. Finish by finding y = 3 and computing 8x + 2y = 32 + 6 = 38.

If you answered 32

That's just 8x — you left off the 2y term. Adding 2(3) = 6 gives 38.

If you answered 44

That's 11x from the elimination step, not the requested value. Divide to get x = 4, find y = 3, then compute 8(4) + 2(3) = 38.

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