The fruit shop shipped 30 boxes of bananas, each weighing 9 kilograms. After selling some, there were 120 kilograms left. How many kilograms were sold?
水果店运来香蕉30箱，每箱9千克，卖了一些后，还剩下120千克，卖了多少千克？
<gadget id="calculator">30 * 9</gadget>
<output>270</output>

<gadget id="calculator">270 - 120</gadget>
<output>150</output>

<result>150</result>