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Question
Let the operation -> be defined by a -> b = a-b/a+b for all numbers a and b, where a (is not equal to) b. If 1 -> 2=--2 -> x, what is the value of x?

A)4
B)3
C)2
D)--2
E)-4

Answer
Hi Tammy,
If a → b = (a-b)/(a+b)
1 → 2 = (1 - 2)/(1 + 2) = -1/3
-2 → x = (-2 - x)/(-2 + x)
Therefore,
-1/3 = (-2 - x)/(-2 + x)
cross-multiplying,
-1(-2 + x) = 3(-2 - x)
2 - x = -6 - 3x
-x + 3x = -6 - 2
2x = -8
x = -4

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