There was some rice in the cafeteria, but I bought 18 more bags this week. After eating 22 bags, there are still 3 bags left. How many bags of rice did the cafeteria have?
食堂原来有一些大米，本周又买来18袋，吃掉了22袋后还剩3袋．食堂原来有大米多少袋？
<gadget id="calculator">3 - 18</gadget>
<output>-15</output>

<gadget id="calculator">22 + (-15)</gadget>
<output>7</output>

<result>7</result>