The cafeteria originally had 240 bags of rice, but another 420 bags were brought in. On average, 3 bags of rice are needed per week. How many weeks will this rice last?
食堂原有240袋大米，又运来420袋．平均每周需要3袋大米．这些大米能够吃多少周？
<gadget id="calculator">240 + 420</gadget>
<output>660</output>

<gadget id="calculator">660 / 3</gadget>
<output>220</output>

<result>220</result>