[tex] \bf \stackrel{f(5)=6}{\begin{array}{l|lllllllll}
x&0&\boxed{5}&10&15&20&25&30&35&40\\\\
f(x)&5&\boxed{6}&7&8&9&10&11&12&13
\end{array}}
\\\\\\
\stackrel{f(15)=8}{\begin{array}{l|lllllllll}
x&0&5&10&\boxed{15}&20&25&30&35&40\\\\
f(x)&5&6&7&\boxed{8}&9&10&11&12&13
\end{array}} [/tex]
