There are 436 passengers on a train, and they get off at Ningyang Station. When a=189, how many people are in the car at this time?
一列火车上有436名乘客，在宁阳站下去a名．当a=189时，这时车上有多少人？
<gadget id="calculator">436 - 189</gadget>
<output>247</output>

<result>247</result>