Xiao Ming and Xiao Hua are 6 kilometers apart. Xiao Ming is in front and Xiao Hua is behind. The two start at the same time. After 2 hours, Xiao Hua catches up with Xiao Ming. Xiao Hua travels 8 kilometers per hour. How many kilometers does Xiao Ming travel per hour? ?
小明、小华两人相距6千米，小明在前，小华在后，两人同时出发，2小时后小华追上小明，小华每小时行8千米，小明每小时行多少千米？
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">8 - 3</gadget>
<output>5</output>

<result>5</result>