The fruit shop shipped back 15 boxes of apples, each weighing 30 kilograms. After selling for a week, there were still 9 boxes left. How many kilograms were sold?
水果店运回15箱苹果，每箱重30千克，卖了一周后还剩9箱，卖了多少千克？
<gadget id="calculator">15 - 9</gadget>
<output>6</output>

<gadget id="calculator">6 * 30</gadget>
<output>180</output>

<result>180</result>