The distance between A and B is 38 kilometers. Xiao Wang starts from A and walks to B, and Xiao Li starts from B to A. It is known that Xiao Wang travels 5 kilometers per hour. Xiao Wang walked for 4 hours before Xiao Li started. After Xiao Li walked for 2 hours, the two met. How many kilometers does Xiao Li travel per hour?
甲乙两地相距38千米，小王从甲地出发向乙地行走，小李从乙地出发向甲地而来．己知小王每小时行5千米，小王先走4小时后，小李才出发，小李走2小时后，两人相遇．小李每小时行多少千米？
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">38 - 20</gadget>
<output>18</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">9 - 5</gadget>
<output>4</output>

<result>4</result>