Aunt Zhang from the landscaping office sprayed 820 apple trees from 7:00 am to 11:00 am. How many apple trees does she spray on average per hour?
园林绿化所的张阿姨早晨7时到11时，共给820棵苹果树喷了药水，她平均每小时喷多少棵？
<gadget id="calculator">11 - 7</gadget>
<output>4</output>

<gadget id="calculator">820 / 4</gadget>
<output>205</output>

<result>205</result>