My mother has to walk 3 kilometers from home to the factory. Once, she walked 2 kilometers to work, then went home to pick up a very important tool, and then went to the factory. How many kilometers did mom walk to work this time?
妈妈从家里到工厂要走3千米，一次，她上班走了2千米，又回家取一很重要工具，再到工厂．这次妈妈上班一共走了多少千米？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<result>7</result>