How to move a picture to the left

Hi folks,
  I am using the following code to import picture:

\hspace{-15mm} 
\begin{center}
\begin{figure}[!htb]
\vspace*{-15mm} 
\par
\begin{center}
%\epsfig{file=math.eps}%, scale=0.80,angle=0}\vspace*{-8mm}
\includegraphics[scale=0.9]{results/may_sd_missing.pdf}\vspace*{-25mm} {}
\vspace*{0mm}
\end{center}
\caption{All school districts of Ohio in 2010.}
\label{ohsd}
\end{figure}
\end{center}

But the margin of the right is smaller than the left; I would like to move the picture about half of inch to the left. Could someone help me with that?
Thanks,
Wu 

P.S. another question:
If I turn the picture around 90 degree by this command:
\begin{center}
\begin{figure}[!htb]
\begin{center}
%\epsfig{file=math.eps}%, scale=0.80,angle=90}\vspace*{-8mm}
\includegraphics[scale=0.9]{results/may_sd_missing.pdf}\vspace*{-25mm} {}
\end{center}
\caption{All school districts of Ohio in 2010.}
\label{ohsd}
\end{figure}
\end{center}

The picture is turned, but the caption is still as before. Is there any way that I turn the picture and caption together?

Thanks totally!


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