A room measures 12 feet in the North-South direction, 15 feet in the East-West Direction, and its ceiling is 10 feet high. Let $t$ denote the the angle that the line from the bottom Southeast corner to the top Northwest corner of the room forms with the floor. Then
$\tan t =$ .
Hint: This is much like the box problem on set 3. Consider the right triangle formed by the line from the bottom Southeast corner to the bottom Northwest corner, the line from the bottom Southeast Corner to the top Northwest corner, and the line from the bottom Northwest corner to the top Northwest corner.