documentclass[a4paper,12pt]{article}
usepackage{graphicx}
begin{document}
begin{figure}[htb]
centering
  begin{tabular}{@{}c@{}}
    includegraphics[width=.5textwidth]{example-image} \
    includegraphics[width=.5textwidth]{example-image} \
    includegraphics[width=.2textwidth]{example-image}
  end{tabular}
end{figure}
end{document}