documentclass[]{article}
begin{document}
begin{tabbing}
hspace{0.8em} hspace{6em} = textit{Paul} hspace{1.5em} =
textit{thinks} hspace{2.8em} = textit{that} hspace{2.5em} =
textit{John} hspace{1.2em} = textit{sleeps}\~\
hspace{0.8em}$(14)$ hspace{5em} = $n$ hspace{2em} = $s/(n)[n]$
hspace{2em} = $n/[s]$ hspace{3em} = $n$ hspace{2em} = $s/(n)$\
hspace{0.8em}$(15)$ hspace{5em} > $n$ hspace{2em} > $s/(n)[n]$
hspace{2em} > $n/[s]$ hspace{4.8em} = $s$\
hspace{0.8em}$(16)$ hspace{5em} > $n$ hspace{2em} > $s/(n)[n]$
hspace{5em} = $n$\
hspace{0.8em}$(17)$ hspace{5em} > > = hspace{2.5em} $s.$
end{tabbing}
end{document}

documentclass[]{article}
usepackage[english]{babel}
usepackage[utf8]{inputenc}
usepackage{tikz}
usetikzlibrary{calc}
usepackage{booktabs}

newcommand{tikzmark}[1]{tikz[overlay,remember picture] node (#1) {};}
newcommand{DrawBox}[3][]{%
    tikz[overlay,remember picture]{
    draw[black,#1]
      ($(#2)+(-0.5em,2.0ex)$) rectangle
      ($(#3)+(0.75em,-0.75ex)$);}
}

begin{document}
begin{tabbing}
hspace{0.8em} hspace{6em} = textit{Paul} hspace{1.5em} =
textit{thinks} hspace{2.8em} = textit{that} hspace{2.5em} =
textit{John} hspace{1.2em} = textit{sleeps}\~\
hspace{0.8em}$(14)$     hspace{5em} = $n$ hspace{2em} = $s/(n)[n]$
hspace{2em} = $n/[s]$ hspace{3em} = tikzmark{top left 1} $n$hspace{2em} = $s/(n)$\
hspace{0.8em}$(15)$     hspace{5em} > $n$ hspace{2em} > $s/(n)[n]$ hspace{2em} > $n/[s]$ hspace{4.8em} = $s$ hspace{20pt}tikzmark{bottom right 1} \
hspace{0.8em}$(16)$     hspace{5em} > $n$ hspace{2em} > $s/(n)[n]$
hspace{5em} = $n$\
hspace{0.8em}$(17)$ hspace{5em} > > = hspace{2.5em} $s.$
end{tabbing}

DrawBox[thin, black]{top left 1}{bottom right 1}

end{document}