A box of apples weighs 20 kilograms. The store ships 60 boxes of apples and sells 45 boxes. How many kilograms are left?
一箱苹果重20千克，商店运来60箱苹果，卖去45箱，还剩多少千克？
<gadget id="calculator">60 - 45</gadget>
<output>15</output>

<gadget id="calculator">15 * 20</gadget>
<output>300</output>

<result>300</result>