<<< native
[ EArray
    [ AlignCenter ]
    [ [ [ EGrouped
            [ EIdentifier "x"
            , ESymbol Bin "+"
            , EDelimited
                "("
                ")"
                [ Right (EFraction NormalFrac (ENumber "2") (ENumber "3")) ]
            ]
        ]
      ]
    , [ [ EDelimited
            ""
            ")"
            [ Right (EIdentifier "x")
            , Right (ESymbol Bin "+")
            , Right (EOver False (ESymbol Open "(") (ESymbol Bin "-"))
            , Right (EFraction NormalFrac (ENumber "2") (ENumber "3"))
            ]
        ]
      ]
    ]
]
>>> tex
\begin{matrix}
{x + \left( \frac{2}{3} \right)} \\
\left. x + \overset{-}{(}\frac{2}{3} \right)
\end{matrix}