[Tex/LaTex] 3 or 4 tikz figures side-by-side

graphicssubfloats

How could I have a figure with 3 or 4 subfigures side-by-side in the same row? I've tried it once but the best I had was only 2 subfigures side-by-side in the same row.

My code so far is:

\documentclass[12pt,a4paper,titlepage,twoside,openright]{article}
\usepackage[english,greek]{babel}
\usepackage{ucs} 
\usepackage[utf8x]{inputenc}
\usepackage[usenames,dvipsnames]{xcolor}
\usepackage{tikz}
\usepackage{tkz-tab}
\usepackage{caption}
\usepackage{latexsym}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{subcaption} 

\begin{document}
\begin{figure}
     \begin{subfigure}[b]{0.30\textwidth}
\centering
        \begin{tikzpicture}
 \draw (0,3) node[left] {$\text{A}$} to[out=0,in=90] (3,0) node[below]{$\text{B}$};
    \draw[->, very thick] (-.1,0) -- (4,0) node[below] {$\text{αγαθό Α}$};
    \draw[->, very thick] (0,-.1) -- (0,4) node[left]{$\text{αγαθό Β}$};
\draw[ForestGreen] (0,2)  node[left] {$\text{Η}$} to [out=0, in=90] (2,0)node[below]{$\text{Θ}$};
\draw[<-, Cyan] (45:2.1) -- (45:2.9);
\end{tikzpicture}
    \label{fig:subfig8}
          \caption{}
       \end{subfigure}
     \begin{subfigure}[b]{0.30\textwidth}
\centering
           \begin{tikzpicture}
\draw (0,3) node[left] {$\text{A}$} to[out=0,in=90] (3,0) node[below]{$\text{B}$};
    \draw[->, very thick] (-.1,0) -- (4,0) node[below] {$\text{αγαθό Α}$};
    \draw[->, very thick] (0,-.1) -- (0,4) node[left]{$\text{αγαθό Β}$};
\draw[ForestGreen] (0,2.7)  node[left] {$\text{Γ}$} to [out=0, in=90] (1.5,0)node[below]{$\text{Δ}$};
\draw[<-, Cyan] (45:2.2) -- (45:2.9);
\end{tikzpicture}
    \label{fig:subfig9}
          \caption{}
          \end{subfigure}
     \begin{subfigure}[b]{0.35\textwidth}
\centering
        \begin{tikzpicture}
\draw (0,3) node[left] {$\text{A}$} to[out=0,in=90] (3,0) node[below]{$\text{B}$};
    \draw[->, very thick] (-.1,0) -- (4,0) node[below] {$\text{αγαθό Α}$};
    \draw[->, very thick] (0,-.1) -- (0,4) node[left]{$\text{αγαθό Β}$};
\draw[ForestGreen] (0,1.5)  node[left] {$\text{E}$} to [out=0, in=90] (2.5,0)node[below]{$\text{Z}$};
\draw[<-, Cyan] (45:2.1) -- (45:2.5);
\end{tikzpicture}
\label{fig:subfig10}
          \caption{}
     \end{subfigure}
\captionof{figure}{τεχνολογία και στα δυο αγαθά} \label{fig:subfig1.a.4}
 \end{figure}

\end{document}

Best Answer

The following code is used for 3, it requires the subcaption package. If have more than 3 change the 0.30\textwidth parameter of the subfigure to resize each of them accordingly

 \begin{figure}
     \begin{subfigure}[b]{0.30\textwidth}
          \centering
          \resizebox{\linewidth}{!}{\input{figures/a.tikz}}  
          \caption{Caption A}
          \label{fig:A}
     \end{subfigure}
     \begin{subfigure}[b]{0.30\textwidth}
          \centering
          \resizebox{\linewidth}{!}{\input{figures/b.tikz}}  
          \caption{Caption B}
          \label{fig:B}
     \end{subfigure}
     \begin{subfigure}[b]{0.30\textwidth}
          \centering
          \resizebox{\linewidth}{!}{\input{figures/c.tikz}}  
          \caption{Caption C}
          \label{fig:C}
     \end{subfigure}
 \end{figure}

EDIT: I've taken the time to fix your code. You were missing the \resizebox in order to properly locate your tikz figures. See code and results below

\documentclass[12pt,a4paper,titlepage,twoside,openright]{article}
\usepackage[english,greek]{babel}
\usepackage{ucs} 
\usepackage[utf8x]{inputenc}
\usepackage[usenames,dvipsnames]{xcolor}
\usepackage{tikz}
\usepackage{tkz-tab}
\usepackage{caption}
\usepackage{latexsym}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{subcaption} 

\begin{document}
\begin{figure}
    \begin{subfigure}[b]{0.32\textwidth}
        \centering
        \resizebox{\linewidth}{!}{
            \begin{tikzpicture}
                \draw (0,3) node[left] {$\text{A}$} to[out=0,in=90] (3,0) node[below]{$\text{B}$};
                \draw[->, very thick] (-.1,0) -- (4,0) node[below] {$\text{αγαθό Α}$};
                \draw[->, very thick] (0,-.1) -- (0,4) node[left]{$\text{αγαθό Β}$};
                \draw[ForestGreen] (0,2)  node[left] {$\text{Η}$} to [out=0, in=90] (2,0)node[below]{$\text{Θ}$};
                \draw[<-, Cyan] (45:2.1) -- (45:2.9);
            \end{tikzpicture}
        }
        \caption{Subfigure A}
        \label{fig:subfig8}
    \end{subfigure}
    \begin{subfigure}[b]{0.32\textwidth}
    \centering
        \resizebox{\linewidth}{!}{
            \begin{tikzpicture}
                \draw (0,3) node[left] {$\text{A}$} to[out=0,in=90] (3,0) node[below]{$\text{B}$};
                \draw[->, very thick] (-.1,0) -- (4,0) node[below] {$\text{αγαθό Α}$};
                \draw[->, very thick] (0,-.1) -- (0,4) node[left]{$\text{αγαθό Β}$};
                \draw[ForestGreen] (0,2.7)  node[left] {$\text{Γ}$} to [out=0, in=90] (1.5,0)node[below]{$\text{Δ}$};
                \draw[<-, Cyan] (45:2.2) -- (45:2.9);
            \end{tikzpicture}
        }
        \caption{Subfigure B}   
        \label{fig:subfig9}
    \end{subfigure}
    \begin{subfigure}[b]{0.32\textwidth}
        \centering
        \resizebox{\linewidth}{!}{
            \begin{tikzpicture}
                \draw (0,3) node[left] {$\text{A}$} to[out=0,in=90] (3,0) node[below]{$\text{B}$};
                \draw[->, very thick] (-.1,0) -- (4,0) node[below] {$\text{αγαθό Α}$};
                \draw[->, very thick] (0,-.1) -- (0,4) node[left]{$\text{αγαθό Β}$};
                \draw[ForestGreen] (0,1.5)  node[left] {$\text{E}$} to [out=0, in=90] (2.5,0)node[below]{$\text{Z}$};
                \draw[<-, Cyan] (45:2.1) -- (45:2.5);
            \end{tikzpicture}
        }
        \caption{Subfigure C}
        \label{fig:subfig10}
    \end{subfigure}
\caption{τεχνολογία και στα δυο αγαθά} 
\label{fig:subfig1.a.4}
\end{figure}

\end{document}

enter image description here

I hope this helps!

Update: Fixed missing { in resizeboxes.