Hey everyone, I really have a problem with these paragraph and I can't translate it to pdf. Can't fix it on my own. Can someone help me?

\begin{tabbing}
\hspace{1.5em}\=$[x]._{(\textbf{S}XY)z} =
\textbf{S}([x]._{\textbf{S}xy})([x]._{z}) =$
\\[1ex]
\>$textbf{S}(\textbf{S}([x]._{\textbf{S}x})(x_y))([x]._z)=\textbf{S}(\textbf{SS}(\textbf{K}y))(\textbf{ K}z)$
\\
\>$[x]._{xz(yz)} = \textbf{S}([x]._{xz})([x]_{yz}) =
\textbf{S}(\textbf{S}([x]._x))([x]._z)) = $
\\
\>$(\textbf{S}([x]._y)([x]._z)) =
\textbf{S}(\textbf{SI}(\textbf{K}z))(\textbf{S}(\t extbf{K}(yz)))$
\end{tabbing}

The formula should be looking like this : [x].(Sxy)z = S([x].Sxy)([x].z) = S(S([x].Sx)([x.y]))([x].z) = S(SS(Ky))(Kz)
[x].xz(yz) = S([x].xz)([x].yz) = S(S([x].x)([x]).z)(S([x].y)([x].z))=S(SI(Kz))(S(K(yz)))