Wang Ming set off from A to B at 7:00 a.m., 3 kilometers per hour. At 11:00 a.m., Zhang Cheng was sent to catch up with Wang Ming. If he caught up in 6 hours, how many kilometers would Zhang Cheng walk per hour?
王明上午七时从甲地出发到乙地去，每小时3千米，上午十一时因事派张诚去追赶王明，6小时追上，张诚每小时走多少千米？
<gadget id="calculator">11 - 7</gadget>
<output>4</output>

<gadget id="calculator">3 / 6</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 * (1/2)</gadget>
<output>2</output>

<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<result>5</result>