There are 3 people in Zhang Hong's family, with a living area of 84 square meters; Li Tian's family has 4 people, with a living area of 104 square meters. Which family has the largest per capita living area? How big is it? What more questions can you ask. Please write it down and answer it.
张红家3口人，居住面积是84平方米；李天家4口人，居住面积是104平方米．谁家的人均居住面积大？大多少？你还能提出什么问题．请写出来，并解答．
<gadget id="calculator">104 - 84</gadget>
<output>20</output>

<result>20</result>