Xiaolong and Xiaoyan live in the same building, and the number of stairs between two adjacent floors of this building is the same. Xiaoyan lives on the 5th floor and has to take 72 stairs to go home, and Xiaolong has to take 108 stairs to go home. Which floor does Xiaolong live on?
小龙和小燕住在同一幢楼里，这幛楼相邻两层间的楼梯级数相同．小燕住在5楼，回家要走72级楼梯，小龙回家要走108级楼梯．小龙住在几楼？
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">72 / 4</gadget>
<output>18</output>

<gadget id="calculator">108 / 18</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>