The fruit store shipped 650 kilograms of pears, and 15 boxes have been sold, with an average of 20 kilograms per box. How many kilograms are left?
水果店运来650千克梨，已经卖了15箱，平均每箱20千克，还剩多少千克？
<gadget id="calculator">20 * 15</gadget>
<output>300</output>

<gadget id="calculator">650 - 300</gadget>
<output>350</output>

<result>350</result>