\begin{equation}
\begin{tikzpicture}[scale=0.67, baseline={([yshift=-1pt]current bounding box.north)}]
    % axis, arrow style to-to
    \draw[{To[scale=1.3]}-{To[scale=1.3]}, line width=1pt] (-10.4, 0) -- (10.4, 0);
    % tick marks
    \foreach \x in {-10,-9,...,10}
        \draw[shift={(\x,0)},color=black, line width=1pt] (0pt,-14pt) -- (0pt,0pt);
    % numbers along each axis
    \foreach \x in {-10}
        \draw[shift={(\x-0.3,-0.8)},color=black] node[font=\large,text height=12pt] {$\x$};
    \foreach \x in {0,10}
        \draw[shift={(\x,-0.8)},color=black] node[font=\large,text height=12pt] {$\x$};
    \draw[shift={(<<startval>>,-0.8)},color=black] node[font=\large,text height=12pt] {$<<startvaltxt>>$};
    \draw[shift={(<<endval>>,-0.8)},color=black] node[font=\large,text height=12pt] {$<<endvaltxt>>$};
    % dots
    \filldraw[black] (<<startval>>,0) circle (4pt) node[above,yshift=-2pt] (a) {};
    \filldraw[black] (<<endval>>,0) circle (4pt) node[above,yshift=-2pt] (b) {};
    % arrow
    \draw[-{To[scale=1.3, bend]},line width=1pt, color=black] (a.north)  .. controls  +(north:\jumpheight mm) and +(north:\jumpheight mm) .. node[above=2pt,xshift=-6pt,font=\large,text height=10pt] {$<<changevaltxt>>$} (b.north); % for addition
    % equation at right end
    \node [font=\large, anchor=east] at (15,1.65){$<<equtxt>>$};
\end{tikzpicture}
\end{equation}