Since angles \( m\angle 1 \) and \( m\angle 3 \) are vertical angles, they are equal. Therefore, we can set their measurements equal to each other:
\[ m\angle 1 = m\angle 3 \]
Substituting the expressions for the angles:
\[ 2x + 26 = 14 \]
To solve for \( x \), first, subtract 26 from both sides:
\[ 2x = 14 - 26 \]
\[ 2x = -12 \]
Next, divide both sides by 2:
\[ x = -6 \]
Thus, the value of \( x \) is
\[ \boxed{-6} \]