A tractor works for 5 hours in the morning, cultivates an average of 15 acres per hour, and works for 3 hours in the afternoon, with a total of 36 acres of cultivated land. How many acres does the tractor cultivate per hour on average?
一台拖拉机上午工作5小时，平均每小时耕地15公亩，下午工作3小时，共耕地36公亩，求拖拉机一天平均每小时耕地多少公亩？
<gadget id="calculator">15 * 5</gadget>
<output>75</output>

<gadget id="calculator">75 + 36</gadget>
<output>111</output>

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

<gadget id="calculator">111 / 8</gadget>
<output>111/8 = around 13.875</output>

<result>111/8 = around 13.875</result>