Hello I have 7 figures in latex. I want to make all those figures to have the same width and height, Here is what I have tried till now. However as you can see in the result, the figures have not the same height and width. I appreciate if anyone can help me.
\begin{figure*}
\centering
%\vspace{-2\baselineskip}
\begin{subfigure}[b]{0.3\textwidth}
%\baselineskip
%\includegraphics[height=8cm, width=18cm]{out_1.png}
\includegraphics[height=8cm\hskip, width=18cm]{out_1.png}
\end{subfigure}
%\quad
\begin{subfigure}[b]{0.3\textwidth}
\includegraphics[height=8cm\hskip, width=18cm]{out_2.png}
\end{subfigure}
\vspace{-11\baselineskip}
%\quad
\begin{subfigure}[b]{0.3\textwidth}
\includegraphics[height=8cm\hskip, width=18cm]{out_3.png}
\end{subfigure}
\begin{subfigure}[b]{0.3\textwidth}
\includegraphics[height=8cm\hskip, width=18cm]{out_4.png}
\end{subfigure}
%\quad
\vspace{-11\baselineskip}
\begin{subfigure}[b]{0.3\textwidth}
\includegraphics[height=8cm, width=18cm]{out_5.png}
\end{subfigure}
%\quad
\begin{subfigure}[b]{0.3\textwidth}
\includegraphics[height=8cm, width=18cm]{out_6.png}
\end{subfigure}
%\vspace{-11\baselineskip}
\begin{subfigure}[b]{0.3\textwidth}
\includegraphics[height=8cm, width=18cm]{out_7.png}
\end{subfigure}
\end{figure*}