the correct answer for this is the last choice:
It is incorrect because the length of the unknown side is the square root of 7,225.
Use proportions and use letters for unknown measurements
12 - 2x = -2(y - x)
12 - 2x = -2y - (-2x)
12 - 2x = -2y + 2x
12 - 2x - 2x = -2y + 2x - 2x
12 - 4x = -2y
12 - 12 - 4x = -2y - 12
-4x = -2y - 12
-4x/4 = -2y/4 - 12/4
-x = -0.5y - 3
-x/-1 = -0.5y/-1 - 3/-1
x = 0.5y + 3
or
x = 3 + 0.5y