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AlgebraHardInterpreting the solution of a system in context

Algebra practice question

A baker uses 2 eggs for each loaf of brioche and 3 eggs for each sponge cake. One morning she uses 18 eggs to make x loaves and y cakes, and she makes 4 more loaves than cakes. Which of the following is the solution of the system that models this situation?

  1. A. x = 6, y = 2Correct
  2. B. x = 2, y = 6
  3. C. x = 9, y = 0
  4. D. x = 5, y = 1

Answer: A. x = 6, y = 2

2x + 3y = 18 and x = y + 4. Substituting: 2(y + 4) + 3y = 18 → 5y = 10 → y = 2, x = 6. Check: 12 + 6 = 18 and 6 − 2 = 4.

Why the other answers are wrong

B. x = 2, y = 6
2(2) + 3(6) = 22, and 2 is not 4 more than 6.
C. x = 9, y = 0
9 loaves use 18 eggs, but 9 is not 4 more than 0.
D. x = 5, y = 1
2(5) + 3(1) = 13, not 18.

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