Turtles can live a long time. This stem-and-leaf plot shows the ages (in years) of the turtles in the reptile house of the Kalamazoo Zoo:
$$
\begin{array}{c | c@{~~}c@{~~}c@{~~}c@{~~}c@{~~}c}
0 & 1 & 1 & 2 & 5 & 6 & 7 \\
1 & 0 & 0 & 3 & 8 & 9 & \\
2 & 0 & 4 & 6 & 7 && \\
3 & 1 & 6 &&&& \\
4 &&&&&& \\
5 & 4 &&&&& \\
6 & 3 & 7 &&&&
\end{array}
$$
A box turtle and a map turtle escape from the reptile house of the Kalamazoo Zoo. The box turtle is older than the map turtle. The average age of the turtles remaining at the zoo after the escape is 1 year less than the average age before the escape.
What is the age of the escaped box turtle?
