Shelly is on a nature hike. She starts out in a valley and climbs up a hill, stopping at regular intervals to take pictures. The elevation of the land in feet below or above sea level at each place Shelly stops follows the function an = an – 1 + 7. The first place Shelly stops to take a picture is 10 feet below sea level, so a1 = –10. What is the elevation of the sixth place Shelly stops?