X_(1,2)= (-5+7)/6

To simplify the expression \( X_{(1,2)} = \frac{-5 + 7}{6} \):

1. First, calculate the numerator: \[ -5 + 7 = 2 \]

2. Now, substitute this back into the fraction: \[ X_{(1,2)} = \frac{2}{6} \]

3. Finally, simplify the fraction: \[ \frac{2}{6} = \frac{1}{3} \]

So, \( X_{(1,2)} = \frac{1}{3} \).