The teacher took 19 students to the bus, and 7 students were already on the bus. How many students did not get on the bus?
老师带着19名同学去坐车，车上已经坐上了7名同学，还有几名同学没有上车？
<gadget id="calculator">19 - 7</gadget>
<output>12</output>

<result>12</result>