There are 900 kilograms of apples in the store, and 8 boxes of 45 kilograms are sold, how many kilograms of apples are left?
商店有900千克的苹果，卖掉8箱，每箱45千克，还剩多少千克的苹果？
<gadget id="calculator">45 * 8</gadget>
<output>360</output>

<gadget id="calculator">900 - 360</gadget>
<output>540</output>

<result>540</result>