16Hit1600
AlgebraEasySystem for a sum and a difference

Algebra practice question

Two numbers x and y have a sum of 15 and a difference of 3. Which system of equations describes x and y?

  1. A. x + y = 15 and x − y = 3Correct
  2. B. x + y = 3 and x − y = 15
  3. C. xy = 15 and x − y = 3
  4. D. x + y = 15 and x + y = 3

Answer: A. x + y = 15 and x − y = 3

Sum is addition, difference is subtraction.

Why the other answers are wrong

B. x + y = 3 and x − y = 15
The sum and difference are swapped.
C. xy = 15 and x − y = 3
A product is not a sum.
D. x + y = 15 and x + y = 3
The same sum cannot equal two values.

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