A car factory plans to produce 45,000 cars, but in the first half of the year it completed 60% of the plan, and in the second half of the year it completed the same number as the first half of the year. How many cars were actually overproduced?
某汽车厂计划生产汽车45000辆，结果上半年完成计划的60%，下半年完成的与上半年同样多，实际超产多少辆？
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/5) - 1</gadget>
<output>-2/5 = around -0.4</output>

<gadget id="calculator">(3/5) + (-2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">45_000 * (1/5)</gadget>
<output>9_000</output>

<result>9_000</result>