If (A-B-C+D = 13) and (A+B-C-D = 9), what is the value of (B-D)^2? Choose the correct answer: A) 4. B) 8. C) 12. D) 16. E) 64.
EQ1: 4. - B - C + D = 13   EQ2: 4. + B - C - D = 9   (1) Subtract EQ1 from EQ2   4. - B - C + D = 13   - 4. +B - C - D = 9   ------------------------   -2B + 2D = 4   (2) Simplify   -B + D = 2   B - D = -2   (B-D)^2 = (-2)^2 = 4   My answer: 4.
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If (A-B-C+D = 13) and (A+B-C-D = 9), what is the value of (B-D)^2?