A bag of salt weighs 500 grams, and you eat 30 grams a day for 8 days, how many grams are left?
有一包盐重500克，每天吃30克，吃了8天，还剩多少克？
<gadget id="calculator">30 * 8</gadget>
<output>240</output>

<gadget id="calculator">500 - 240</gadget>
<output>260</output>

<result>260</result>