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AlgebraEasyTranslating a word problem into a system

Algebra practice question

Which system of equations describes the statement: the sum of two numbers x and y is 9, and their difference is 1?

  1. A. x + y = 9 and x − y = 1Correct
  2. B. x + y = 1 and x − y = 9
  3. C. xy = 9 and x/y = 1
  4. D. x + y = 9 and x + y = 1

Answer: A. x + y = 9 and x − y = 1

Sum is x + y; difference is x − y.

Why the other answers are wrong

B. x + y = 1 and x − y = 9
Sum and difference are swapped.
C. xy = 9 and x/y = 1
Product and quotient, not sum and difference.
D. x + y = 9 and x + y = 1
Two sums that cannot both be true.

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