The cafeteria shipped 800 kilograms of rice, and after eating for 9 days, there was still 440 kilograms of rice left. How many kilograms were eaten per day on average?
食堂运来800千克大米，吃了9天后还剩下440千克大米，平均每天吃了多少千克？
<gadget id="calculator">800 - 440</gadget>
<output>360</output>

<gadget id="calculator">360 / 9</gadget>
<output>40</output>

<result>40</result>