\documentclass{article}
\usepackage{tabularx}
\usepackage{bidi}
\title{Testing \textsf{tabularx} Package in RTL and LTR}
\author{Vafa Khalighi}
\begin{document}
\maketitle
\section{LTR}
\begin{tabularx}{\linewidth}{|l|p{1.25cm}|p{1.5cm}|X|}\hline
\multicolumn{1}{|c|}{\textbf{Animal}}
  & \textbf{Hair Colour}
  & \multicolumn{2}{c|}{\textbf{Favourite foods}} \\\hline\hline
Elephant & Gray & Peanuts
  & Unshelled, prepared in Sea Salt, and warmed over hot stone grill \\\cline{3-4}
  &  & Cabbage and Greens
  & Sun dried until lightly browned (2-3 days minimum);
    seasoned with Hyperchem super feed \\\cline{4-4}
  & & & Boiled to British standard \\\hline\hline
Lion & Yellow & Elephants & Tartare \\\cline{4-4}
& & & Must be served warm, with no trace of
  buckshot. Gaiminess considered desireable. \\\hline
\end{tabularx}
\section{RTL}

\setRTL
\begin{tabularx}{\linewidth}{|r|p{1.25cm}|p{1.5cm}|X|}\hline
\multicolumn{1}{|c|}{\textbf{Animal}}
  & \textbf{Hair Colour}
  & \multicolumn{2}{c|}{\textbf{Favourite foods}} \\\hline\hline
Elephant & Gray & Peanuts
  & Unshelled, prepared in Sea Salt, and warmed over hot stone grill \\\cline{3-4}
  &  & Cabbage and Greens
  & Sun dried until lightly browned (2-3 days minimum);
    seasoned with Hyperchem super feed \\\cline{4-4}
  & & & Boiled to British standard \\\hline\hline
Lion & Yellow & Elephants & Tartare \\\cline{4-4}
& & & Must be served warm, with no trace of
  buckshot. Gaiminess considered desireable. \\\hline
\end{tabularx}
\end{document}
