Answer: 2y (choice A)
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Step-by-step explanation:
x, y, and z are consecutive multiples of 4.
For example, they could be x = 8, y = 12, and z = 16
The gap from x to y is 4 units.
This means y = x+4 which rearranges to x = y-4
Similarly, z = y+4
The sequence {x, y, z} is equivalent to {y-4, y, y+4}
Therefore,
x+z = (y-4)+(y+4) = 2y
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Going back to the example of x = 8, y = 12, z = 16 has us get
x+z = 8+16 = 24 which is exactly double that of the middle term y = 12.
This example helps confirm the answer.